Core/Player: cleanup function CheckInstanceLoginValid

sql/updates/world/2015_11_27_00_world_355.sql

@@ -0,0 +1,3 @@
+DELETE FROM `trinity_string` WHERE `entry` = 11010;
+INSERT INTO `trinity_string` (`entry`,`content_default`) VALUES
+(11010, 'You didn\'t get kicked out of the instance even if Player::CheckInstanceLoginValid() returned false and without .gm on flag');