Improved multi case initial reading

When creating a multi case group from multiple files, read grid from first file.
The main grid from the first case is reused for the other cases.
NOTE: Metadata and well information is not read for the other cases
p4#: 20655

ApplicationCode/FileInterface/RifReaderEclipseOutput.cpp

@@ -430,8 +430,9 @@ bool RifReaderEclipseOutput::openAndReadActiveCellData(const QString& fileName,
     progInfo.setNextProgressIncrement(50);
     progInfo.setProgressDescription("Reading meta data");
 
-    // Build results meta data
-    if (!buildMetaData()) return false;
+    // Reading of metadata and well cells is not performed here
+    //if (!buildMetaData()) return false;
+    // readWellCells();
 
     return true;
 }