When the test failed, it never released the blocking slot, so the
tested thread remained blocked indefinitely. Blacklisting doesn't
rescue that: the test run gets killed by Coin's watchdog.
Use a QScopeGuard() to release the clocked slot on failure.
replacing the release that was happening only on success.
As drive-by clean-up, smarten up the code a little and remove an
unused enum.
Pick-to: 6.2 6.1 5.15
Change-Id: Ie035dafe6e4b1d82aea5de38ceb31c0f7fcf81d7
Reviewed-by: Sona Kurazyan <sona.kurazyan@qt.io>
2684deaf26