ProcessLauncher: stop awaiting for ready read when finished

In case the user called waitForReadyRead() and we have
received the finished signal instead (without receiving
readyRead signals in meantime), we should interrupt
the wait and return false, since there is no point to
wait for future readyRead signals from not running process.

Change-Id: Ib4a770aea6ed562a5bef197eaa51b20c146842f0
Reviewed-by: hjk <hjk@qt.io>
Reviewed-by: <github-actions-qt-creator@cristianadam.eu>

src/libs/utils/launchersocket.cpp

@@ -559,6 +559,9 @@ bool LauncherHandle::waitForSignal(int msecs, CallerHandle::SignalType newSignal
             return true;
         if (wasCanceled)
             return true; // or false? is false only in case of timeout?
+        const bool finishedSignalFlushed = flushedSignals.contains(CallerHandle::SignalType::Finished);
+        if (finishedSignalFlushed)
+            return false; // finish has appeared but we were waiting for other signal
     }
     return false;
 }