(fwServicesTest): random fail in startStopTest at l366

What does this MR do?

A wait condition was added to prevent a random crash in fwServicesTest

How to test it?

• Add a sleep in TestService::updating() in TestService.cpp so that it looks like that:

void TestService::updating()
{
    std::this_thread::sleep_for( std::chrono::seconds(1));
    if(m_raiseException)
    {
        throw ::fwCore::Exception("update error");
    }
    m_updateOrder = s_UPDATE_COUNTER++;
}

• Launch fwServicesTest fwServices::ut::AppConfigTest::startStopTest
• Observe the failure
• Checkout the MR
• Recompile, launch again
• Observe that it works

Associated Issues/Merge Requests

• Issues
  • Closes #301 (closed)