Create timer in TransactionPerformanceCollector lazily

[adinauer]

📜 Description

Timer was created even if performance wasn't enabled. Also Timer prevented shutdown.

💡 Motivation and Context

Fixes #2477

💚 How did you test it?

📝 Checklist

• I reviewed the submitted code
• I added tests to verify the changes
• I updated the docs if needed
• No breaking changes

🔮 Next steps

• @stefanosiano can you please help test if this still works correctly

[github-actions]

Performance metrics 🚀

	Plain	With Sentry	Diff
Startup time	322.08 ms	380.45 ms	58.37 ms
Size	1.73 MiB	2.33 MiB	619.47 KiB

Previous results on branch: fix/create-performance-collector-timer-lazily

Startup times

Revision	Plain	With Sentry	Diff
bec6aae	307.14 ms	344.22 ms	37.08 ms

App size

Revision	Plain	With Sentry	Diff
bec6aae	1.73 MiB	2.33 MiB	619.47 KiB

[romtsn]

jeez, here we are again with the Timer stuff :D can we write an integration test that checks for shutdown of a backend app somehow?

[codecov]

Codecov Report

Base: 80.14% // Head: 80.13% // Decreases project coverage by -0.00% ⚠️

Coverage data is based on head (adb859b) compared to base (734e4a5).
Patch coverage: 83.33% of modified lines in pull request are covered.

Additional details and impacted files

@@             Coverage Diff              @@
##               main    #2478      +/-   ##
============================================
- Coverage     80.14%   80.13%   -0.01%     
- Complexity     3872     3873       +1     
============================================
  Files           312      312              
  Lines         14669    14672       +3     
  Branches       1941     1943       +2     
============================================
+ Hits          11756    11758       +2     
  Misses         2153     2153              
- Partials        760      761       +1     

Impacted Files	Coverage Δ
...ava/io/sentry/TransactionPerformanceCollector.java	89.79% <83.33%> (-1.51%)	⬇️

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[adinauer]

can we write an integration test that checks for shutdown of a backend app somehow?

Yeah we should. Created #2479 so we don't forget.