sdk-logs: default event timestamp on emit

[jeet7122]

Fixes #8097

What this changes

*Default event timestamp to clock.now() in SdkLogRecordBuilder.emit() when not explicitly set.

• This aligns behavior with the setTimestamp javadoc (timestamp should default at emit time).
• Updated emit_NoFields test accordingly.

Testing

• Ran :sdk:logs:test

• Opening as a draft PR to coordinate and avoid duplicate work if someone else is already working on this.

[linux-foundation-easycla]

The committers listed above are authorized under a signed CLA.

• ✅ login: jeet7122 / name: Jeet Thakkar (0e6f815, 46a5d01, 7fdc859, cb7fa05)

[jack-berg]

See #8097 (comment)

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 90.32%. Comparing base (b089521) to head (0e6f815).
⚠️ Report is 16 commits behind head on main.

Additional details and impacted files

@@             Coverage Diff              @@
##               main    #8114      +/-   ##
============================================
- Coverage     90.33%   90.32%   -0.01%     
+ Complexity     7614     7612       -2     
============================================
  Files           839      839              
  Lines         22913    22913              
  Branches       2285     2285              
============================================
- Hits          20698    20696       -2     
  Misses         1505     1505              
- Partials        710      712       +2     

☔ View full report in Codecov by Sentry.
📢 Have feedback on the report? Share it here.

🚀 New features to boost your workflow:

• ❄️ Test Analytics: Detect flaky tests, report on failures, and find test suite problems.

[jeet7122]

Thanks for the clarification! I reverted the behavior change and updated the setTimestamp javadoc to align with the spec.

[jeet7122]

I’ve updated the javadocs to align with the spec and pushed the changes.
Could you please take another look when you get a chance?

[jack-berg]

Closing because the issue is already solved in #8104. In the future, look out for existing PRs for an issue to avoid wasted effort. If there's an existing PR, the approach is reasonable, and the author is responsive, it will be preferred over later PRs. Thanks!