MINOR: Optimize EventAccumulator

[dajac]

poll(long timeout, TimeUnit unit) is either used with Long.MAX_VALUE or 0. This patch replaces it with poll and take. It removes the awaitNanos usage.

Committer Checklist (excluded from commit message)

• [ ] Verify design and implementation
• [ ] Verify test coverage and CI build status
• [ ] Verify documentation (including upgrade notes)