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/Commands/RicImportEnsembleFeature.cpp

@@ -112,7 +112,6 @@ void RicImportEnsembleFeature::importSingleEnsemble( const QStringList&
 
     if ( cases.empty() ) return;
 
-    RicImportSummaryCasesFeature::addSummaryCases( cases );
     RimSummaryCaseCollection* ensemble =
         RicCreateSummaryCaseCollectionFeature::groupSummaryCases( cases, ensembleName, true );