AutoTest: Fix special handling for boost exit

...especially for the case where the test output is suppressed.

Change-Id: I7294af9e941d800b8aae65f7c2c6f898f2ac4e46
Reviewed-by: Jarek Kobus <jaroslaw.kobus@qt.io>

src/plugins/autotest/boost/boosttestoutputreader.cpp

@@ -31,12 +31,6 @@ BoostTestOutputReader::BoostTestOutputReader(Process *testApplication,
     , m_logLevel(log)
     , m_reportLevel(report)
 {
-    if (!testApplication)
-        return;
-
-    connect(testApplication, &Process::done, this, [this, testApplication] {
-        onDone(testApplication->exitCode());
-    });
 }
 
 // content of "error:..." / "info:..." / ... messages