MCOL-3395 Always clear dctnry cache on close

The dictionary cache needs to be cleared every time it is closed so that
on bulk insert we don't mix the cache between columns.

writeengine/dictionary/we_dctnry.cpp

@@ -419,8 +419,7 @@ int Dctnry::closeDctnry(bool realClose)
         return rc;
 
     //cout <<"Init called! m_dctnryOID ="  << m_dctnryOID << endl;
-    if (realClose)
-        freeStringCache( );
+    freeStringCache( );
 
     return NO_ERROR;
 }