Fix memory leak for data source ensemble summary (#8919)

* Do not create summary case group twice

* Fix memory leak of objects contained in childArrayFields
Use deleteAllChildObjects to delete objects instead of clear()
Rename collection function clear() -> deleteAllChildObjects

* Early exit for empty path

* Reduce redundant calls to refreshMetaData

ApplicationLibCode/ProjectDataModel/Summary/RimSummaryCaseCollection.cpp

@@ -1098,5 +1098,5 @@ void RimSummaryCaseCollection::refreshMetaData()
 //--------------------------------------------------------------------------------------------------
 void RimSummaryCaseCollection::clearChildNodes()
 {
-    m_dataVectorFolders->clear();
+    m_dataVectorFolders->deleteAllChildObjects();
 }