MXS-3292 Fix bug

The string given to USE must be dequoted before being stored.

query_classifier/qc_sqlite/qc_sqlite.cc

@@ -3271,6 +3271,7 @@ public:
         if (should_collect(QC_COLLECT_DATABASES))
         {
             char* zCopy = MXS_STRNDUP_A(pToken->z, pToken->n);
+            exposed_sqlite3Dequote(zCopy);
 
             m_database_names.push_back(zCopy);
         }