Remove Batch LogRecord&Span Processor configuration via non-standard environment variables

[CosminLazar]

Fixes #
Design discussion issue (if applicable) #

Changes

Removes Batch LogRecord&Span Processor configuration via non-standard environment variables.

For convenience and discoverability, a mapping table from the no longer supported to the supported environment variables is provided here:

No longer supported	Standard equivalent
OTEL_BLRP_SCHEDULE_DELAY_MILLIS	OTEL_BLRP_SCHEDULE_DELAY
OTEL_BLRP_EXPORT_TIMEOUT_MILLIS	OTEL_BLRP_EXPORT_TIMEOUT
OTEL_BSP_SCHEDULE_DELAY_MILLIS	OTEL_BSP_SCHEDULE_DELAY
OTEL_BSP_EXPORT_TIMEOUT_MILLIS	OTEL_BSP_EXPORT_TIMEOUT

Merge requirement checklist

• CONTRIBUTING guidelines followed
• Unit tests added/updated (if applicable)
• Appropriate CHANGELOG.md files updated for non-trivial, user-facing changes
• Changes in public API reviewed (if applicable)

[codecov]

Codecov Report

Attention: 4 lines in your changes are missing coverage. Please review.

Comparison is base (27b19b6) 63.7% compared to head (2522e76) 64.0%.
Report is 1 commits behind head on main.

Files	Patch %	Lines
opentelemetry-sdk/src/trace/span_processor.rs	97.6%	3 Missing ⚠️
opentelemetry-sdk/src/logs/log_processor.rs	98.0%	1 Missing ⚠️

Additional details and impacted files

@@           Coverage Diff           @@
##            main   #1495     +/-   ##
=======================================
+ Coverage   63.7%   64.0%   +0.2%     
=======================================
  Files        142     142             
  Lines      19499   19507      +8     
=======================================
+ Hits       12437   12499     +62     
+ Misses      7062    7008     -54     

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[CosminLazar]

As per our discussion in #1480, I have also replaced the links to the OLTP specification with the actual supported environment variables. If bundling this change with this PR is undesirable, let me know and I will make another PR.