Don't wait in the tesrver idle testing every time around the loop

Don't wait in the tesrver idle testing every time around the loop

If we wait for 100ms 600 times - then the test takes a minute to complete
which is far too long. The purpose of the wait is to give the assistance
thread a chance to catch up. We only do that if the event timeout has
actually expired - otherwise we are waiting for no reason.

Fixes #22156

Reviewed-by: Paul Dale <pauli@openssl.org>
Reviewed-by: Richard Levitte <levitte@openssl.org>
Reviewed-by: Tomas Mraz <tomas@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/22284)