fix: run heartbeat not as uid 1000

[mdelapenya]

What does this PR do?

In the k8s-autodiscover test suite, it sets an env var in heartbeat deployment to not hearbeat process as 1000, returning back to use root.

Why is it important?

I think it's better explained here: elastic/beats#28570

Checklist

• My code follows the style guidelines of this project
• I have commented my code, particularly in hard-to-understand areas
• I have made corresponding changes to the documentation
• I have made corresponding change to the default configuration files
• I have added tests that prove my fix is effective or that my feature works
• I have run the Unit tests (make unit-test), and they are passing locally
• I have run the End-2-End tests for the suite I'm working on, and they are passing locally
• I have noticed new Go dependencies (run make notice in the proper directory)

Author's Checklist

• @jsoriano, what are the implication of running this pod as root again?

How to test this PR locally

kind delete clusters --all && \
TAGS="heartbeat" TIMEOUT_FACTOR=3 LOG_LEVEL=TRACE DEVELOPER_MODE=true \
GITHUB_CHECK_SHA1=81c38fc4c009348d57c92ae85920aed35297a89e \
ELASTIC_APM_ACTIVE=false make -C e2e/_suites/kubernetes-autodiscover functional-test

Related issues

• Relates [Agent] Elastic-Agent-Packaging-Linux is failed (there for e2e-testing pr support) which blocks merges - seems to be a Heartbeat container build problem beats#28570

[elasticmachine]

💚 Build Succeeded

the below badges are clickable and redirect to their specific view in the CI or DOCS

Expand to view the summary

Build stats

• Start Time: 2021-10-20T17:26:55.122+0000

• Duration: 19 min 42 sec

• Commit: 1eff107

Test stats 🧪

Test	Results
Failed	0
Passed	162
Skipped	0
Total	162

💚 Flaky test report

Tests succeeded.

🤖 GitHub comments

To re-run your PR in the CI, just comment with:

• /test : Re-trigger the build.

[andrewvc]

This is fine as a short term fix, but since the root cause is that heartbeat/uid1000 doesn't have perms to read /etc/heartbeat, the better fix would be changing perms there.

[andrewvc]

I've opened elastic/beats#28572 to improve this situation in heartbeat, but we should still try to fix the perms on those files.

[EricDavisX]

ok as a temp fix to unblock Beats prs. other follow ups are logged.

[EricDavisX]

I am confirming from Beats side, and merging.

[andrewvc]

FYI, I have a permanent fix here:elastic/beats#28577 , we really only need this fix in the agent image. Once this is merged you can consider reverting this PR