## Summary of changes
- Add FixedSizeArrayPool and logger overloads to reduce per-log
allocations.
- Add RefStopwatch/StopwatchHelpers/CodeDuration and apply timing to
TraceClock/TracerManagerFactory/Instrumentation and CI processors.
- Lower init logs to Debug for CI protocol writer/sender and processors.

## Reason for change
Reduce allocations and improve timing diagnostics in hot paths.

## Implementation details
- New utility helpers in `Datadog.Trace.Util` for allocation-free timing
and pooling.
- Logging changes to avoid params array allocations in common log paths.
- Timing/log-level tweaks in CI protocol writer/sender and trace
processors.

## Test coverage
CI passes then all changes are good.

## Other details
- Stacked PRs (current marked):
- **CURRENT**: PR1 #8070
  - PR2 #8071
  - PR3 #8072
  - PR4 #8073

## Summary of changes
- Introduce Test Optimization RunId and EnsureRunId with cache folder
lifecycle.
- Add `_DD_INTERNAL_TOPT_RUNID` to config mapping/docs and regenerate
keys.
- Update CI integration tests to set/print RunId for deterministic runs.
- Adjust test helper thread naming for clearer CI debugging.

## Reason for change
Provide a stable RunId before caching work that depends on it and keep
configuration in sync.

## Implementation details
- Add RunId/EnsureRunId to `ITestOptimization`/`TestOptimization` with
environment propagation.
- Update configuration mapping and generated CI visibility keys.
- Update CI integration tests for RunId coverage.

## Test coverage
CI passes then all changes are good.

## Other details
- Stacked PRs (current marked):
  - PR1 #8070
- **CURRENT**: PR2 #8071
  - PR3 #8072
  - PR4 #8073

## Summary of changes
- Add git command caching and telemetry improvements for CI visibility.
- Update GitInfo discovery and CI environment logging.
- Update impacted tests for new git discovery behavior.

JIRA: SDTEST-3226

## Reason for change
Reduce git command overhead and improve visibility into CI git metadata
collection.

## Implementation details
- Disk cache keyed by RunId in GitCommandHelper with safe.directory
handling.
- JSON annotations in ProcessHelpers for cache serialization.
- Adjusted CI runner git discovery logic and tests.

## Test coverage
CI passes then all changes are good.

## Other details
- Stacked PRs (current marked):
  - PR1 #8070
  - PR2 #8071
- **CURRENT**: PR3 #8072
  - PR4 #8073