`testBidirectionalStreamingOnCloseAfterUserFunctionFails` is getting wedged in CI

[glbrntt]

Describe the bug

• testBidirectionalStreamingOnCloseAfterUserFunctionFails seems to get stuck when run in CI and eventually times out.
• This doesn't happen consistently but does happen quite frequently.

Additional information

• This doesn't reproduce locally (on macOS or in Docker)