Deadlock in Test/ClientUpdatesParamsOnGoAway on failure

[dustin-ward]

What version of gRPC are you using?

1.38.0

What version of Go are you using (go version)?

1.16.4

What operating system (Linux, Windows, …) and version?

Linux (Ubuntu 20.04.2 LTS) & zOS

What did you do?

An unrelated network issue caused this test to enter the second conditional statement. Forcing the program to enter this conditional will result in the same issue.

What did you expect to see?

The test should unlock the associated mutex before returning a fatal error message, so the program can properly end execution and report the actual errors.

What did you see instead?

The mutex is never unlocked, so the program will hang at this point.