## Why
Concurrent tests without a tracing subscriber can cache the network policy
callsite as disabled, causing event-capture tests to miss events.
## What changed
- Attach the test event collector directly to the captured future.
- Rebuild the tracing interest cache before running that future while keeping
tracing out of its single-subscriber fast path.
GitOrigin-RevId: 20d6160d26f56ad9fd86afd5107cb4313a5fce73