Summary plot crash fixes (#8595)

Disable assert for duplicated signal connections for now, just ignore everyone but the first one
Temp. workaround for crash when duplicating plot axis properties.
Update test

Fwk/AppFwk/cafProjectDataModel/cafPdmCore/cafPdmCore_UnitTests/cafSignalTest.cpp

@@ -156,14 +156,14 @@ TEST( SignalTest, ObserverDeletion )
     emitter.triggerBasicSignal();
 }
 
-TEST( SignalTest, ConnectSignalTwiceAssert )
-{
-    ASSERT_DEATH(
-        {
-            TestEmitter  emitter;
-            TestObserver observer;
-
-            observer.connectSignalsTwice( &emitter );
-        },
-        "" );
-}
+// TEST( SignalTest, ConnectSignalTwiceAssert )
+//{
+//    ASSERT_DEATH(
+//        {
+//            TestEmitter  emitter;
+//            TestObserver observer;
+//
+//            observer.connectSignalsTwice( &emitter );
+//        },
+//        "" );
+//}

Fwk/AppFwk/cafProjectDataModel/cafPdmCore/cafSignal.h

@@ -137,7 +137,8 @@ public:
                        "Only classes that inherit SignalObserver can connect as an observer of a Signal." );
 
         // Connecting a signal twice is not supported
-        CAF_ASSERT( m_observerCallbacks.find( observer ) == m_observerCallbacks.end() );
+        // CAF_ASSERT( m_observerCallbacks.find( observer ) == m_observerCallbacks.end() );
+        if ( m_observerCallbacks.find( observer ) != m_observerCallbacks.end() ) return;
 
         m_observerCallbacks[observer] = std::make_pair( callback, true );
         observer->addObservedSignal( this );