Dispose DbCommand in DbMetaDataFactory.ExecuteCommand

A static analysis tool has flagged that DbCommand is an IDisposable, so
it should be Disposed() to free up resources.

src/libraries/Common/src/System/Data/ProviderBase/DbMetaDataFactory.cs

@@ -122,7 +122,7 @@ private DataTable ExecuteCommand(DataRow requestedCollectionRow, string?[]? rest
                 throw ADP.TooManyRestrictions(collectionName);
             }
 
-            command = connection.CreateCommand();
+            using command = connection.CreateCommand();
             command.CommandText = sqlCommand;
             command.CommandTimeout = Math.Max(command.CommandTimeout, 180);