Flaky: CIOWebSocketTest.testCorruptFrameWithBadOpcode EADDRINUSE on linuxX64

## Description
`CIOWebSocketTest.testCorruptFrameWithBadOpcode[linuxX64]` fails with `EADDRINUSE` — port conflict from a previous test not releasing the port in time.

## Impact
Intermittent failure on "Native Linux X64" CI check.

## Affected PRs (sample)
- #5426

## Platforms
- Native Linux X64 (linuxX64)

## Suggested investigation
- Add a small delay or use dynamic port allocation (port 0) to avoid port conflicts between tests
- Ensure `ServerSocket.close()` completes before the next test binds to the same port

Start by locating CIOWebSocketTest.testCorruptFrameWithBadOpcode and reproduce it on the Native Linux X64 CI target. Inspect how the test binds and closes its ServerSocket, then verify that repeated runs no longer produce EADDRINUSE and that the affected CI check passes.

Written by the indexing model from the issue text.