[9.18] fix: test: Check read value in upforwd/ans4
The ans4 server wasn't shutting down cleanly sometimes. Check that read returns the expected value for the message length or exit read loop.
Closes #4301 (closed)
Backport of MR !9537 (merged)
The ans4 server wasn't shutting down cleanly sometimes. Check that read returns the expected value for the message length or exit read loop.
Closes #4301 (closed)
Backport of MR !9537 (merged)