[exporter/splunkhec] Fix data race when gzip compression is enabled

[hvaghani221]

Description:
When executing the otel agent with a race flag, it detects some data race in gzip package resulting in invalid index access (i.e. index out of the bound access)

Link to tracking Issue: #17083

Testing:

Ran the OTel agent for a few hours with the race flag enabled

Documentation:

[runforesight]

Foresight Summary

    
Major Impacts

build-and-test-windows duration(4 seconds) has decreased 42 minutes 51 seconds compared to main branch avg(42 minutes 55 seconds).

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⭕  build-and-test-windows workflow has finished in 4 seconds (42 minutes 48 seconds less than main branch avg.) and finished at 19th Dec, 2022.

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Job	Failed Steps	Tests
windows-unittest-matrix	-     🔗	N/A	See Details
windows-unittest	-     🔗	N/A	See Details

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✅  check-links workflow has finished in 43 seconds (2 minutes 50 seconds less than main branch avg.) and finished at 19th Dec, 2022.

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Job	Failed Steps	Tests
changed files	-     🔗	N/A	See Details
check-links	-     🔗	N/A	See Details

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✅  tracegen workflow has finished in 1 minute 7 seconds (2 minutes 47 seconds less than main branch avg.) and finished at 19th Dec, 2022.

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Job	Failed Steps	Tests
build-dev	-     🔗	N/A	See Details
publish-latest	-     🔗	N/A	See Details
publish-stable	-     🔗	N/A	See Details

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✅  changelog workflow has finished in 1 minute 38 seconds (7 minutes 8 seconds less than main branch avg.) and finished at 19th Dec, 2022.

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Job	Failed Steps	Tests
changelog	-     🔗	N/A	See Details

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✅  prometheus-compliance-tests workflow has finished in 3 minutes 15 seconds (6 minutes 39 seconds less than main branch avg.) and finished at 19th Dec, 2022.

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Job	Failed Steps	Tests
prometheus-compliance-tests	-     🔗	✅ 21  ❌ 0  ⏭ 0    🔗	See Details

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✅  build-and-test workflow has finished in 36 minutes 12 seconds (23 minutes 58 seconds less than main branch avg.) and finished at 19th Dec, 2022.

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Job	Failed Steps	Tests
unittest-matrix (1.18, internal)	-     🔗	✅ 592  ❌ 0  ⏭ 0    🔗	See Details
unittest-matrix (1.19, internal)	-     🔗	✅ 592  ❌ 0  ⏭ 0    🔗	See Details
correctness-metrics	-     🔗	✅ 2  ❌ 0  ⏭ 0    🔗	See Details
unittest-matrix (1.19, processor)	-     🔗	✅ 1474  ❌ 0  ⏭ 0    🔗	See Details
correctness-traces	-     🔗	✅ 17  ❌ 0  ⏭ 0    🔗	See Details
unittest-matrix (1.19, extension)	-     🔗	✅ 528  ❌ 0  ⏭ 0    🔗	See Details
unittest-matrix (1.18, processor)	-     🔗	✅ 1474  ❌ 0  ⏭ 0    🔗	See Details
unittest-matrix (1.18, extension)	-     🔗	✅ 528  ❌ 0  ⏭ 0    🔗	See Details
unittest-matrix (1.19, receiver-0)	-     🔗	✅ 2539  ❌ 0  ⏭ 0    🔗	See Details
unittest-matrix (1.18, receiver-0)	-     🔗	✅ 2539  ❌ 0  ⏭ 0    🔗	See Details
unittest-matrix (1.19, other)	-     🔗	✅ 4394  ❌ 0  ⏭ 0    🔗	See Details
unittest-matrix (1.18, exporter)	-     🔗	✅ 2456  ❌ 0  ⏭ 0    🔗	See Details
unittest-matrix (1.19, receiver-1)	-     🔗	✅ 1854  ❌ 0  ⏭ 0    🔗	See Details
unittest-matrix (1.19, exporter)	-     🔗	✅ 2456  ❌ 0  ⏭ 0    🔗	See Details
unittest-matrix (1.18, other)	-     🔗	✅ 4394  ❌ 0  ⏭ 0    🔗	See Details
unittest-matrix (1.18, receiver-1)	-     🔗	✅ 1854  ❌ 0  ⏭ 0    🔗	See Details
integration-tests	-     🔗	✅ 55  ❌ 0  ⏭ 0    🔗	See Details
setup-environment	-     🔗	N/A	See Details
check-collector-module-version	-     🔗	N/A	See Details
lint-matrix (receiver-0)	-     🔗	N/A	See Details
lint-matrix (receiver-1)	-     🔗	N/A	See Details
lint-matrix (processor)	-     🔗	N/A	See Details
lint-matrix (exporter)	-     🔗	N/A	See Details
lint-matrix (extension)	-     🔗	N/A	See Details
lint-matrix (internal)	-     🔗	N/A	See Details
lint-matrix (other)	-     🔗	N/A	See Details
build-examples	-     🔗	N/A	See Details
check-codeowners	-     🔗	N/A	See Details
checks	-     🔗	N/A	See Details
lint	-     🔗	N/A	See Details
unittest (1.19)	-     🔗	N/A	See Details
unittest (1.18)	-     🔗	N/A	See Details
cross-compile (darwin, amd64)	-     🔗	N/A	See Details
cross-compile (darwin, arm64)	-     🔗	N/A	See Details
cross-compile (linux, 386)	-     🔗	N/A	See Details
cross-compile (linux, amd64)	-     🔗	N/A	See Details
cross-compile (linux, arm)	-     🔗	N/A	See Details
cross-compile (linux, arm64)	-     🔗	N/A	See Details
cross-compile (linux, ppc64le)	-     🔗	N/A	See Details
cross-compile (windows, 386)	-     🔗	N/A	See Details
cross-compile (windows, amd64)	-     🔗	N/A	See Details
build-package (deb)	-     🔗	N/A	See Details
build-package (rpm)	-     🔗	N/A	See Details
windows-msi	-     🔗	N/A	See Details
publish-check	-     🔗	N/A	See Details
publish-stable	-     🔗	N/A	See Details
publish-dev	-     🔗	N/A	See Details

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✅  load-tests workflow has finished in 8 minutes 41 seconds (8 minutes 45 seconds less than main branch avg.) and finished at 19th Dec, 2022.

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Job	Failed Steps	Tests
loadtest (TestTraceAttributesProcessor)	-     🔗	✅ 3  ❌ 0  ⏭ 0    🔗	See Details
loadtest (TestIdleMode)	-     🔗	✅ 1  ❌ 0  ⏭ 0    🔗	See Details
loadtest (TestTraceNoBackend10kSPS|TestTrace1kSPSWithAttrs)	-     🔗	✅ 8  ❌ 0  ⏭ 0    🔗	See Details
loadtest (TestMetric10kDPS|TestMetricsFromFile)	-     🔗	✅ 6  ❌ 0  ⏭ 0    🔗	See Details
loadtest (TestTraceBallast1kSPSWithAttrs|TestTraceBallast1kSPSAddAttrs)	-     🔗	✅ 10  ❌ 0  ⏭ 0    🔗	See Details
loadtest (TestMetricResourceProcessor|TestTrace10kSPS)	-     🔗	✅ 12  ❌ 0  ⏭ 0    🔗	See Details
loadtest (TestBallastMemory|TestLog10kDPS)	-     🔗	✅ 19  ❌ 0  ⏭ 0    🔗	See Details
setup-environment	-     🔗	N/A	See Details

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[dmitryax]

Thanks @harshit-splunk