Fixup hardcore handling on join in 1.8->1.9 (ViaVersion#3946)

* Fix players crashing when logging into a 1.8 server on hardcore mode, Fixes ViaVersion#3944

* Requested change to ViaVersion#3944 fix

Author: LeonTG

common/src/main/java/com/viaversion/viaversion/protocols/v1_8to1_9/rewriter/PlayerPacketRewriter1_9.java

@@ -196,7 +196,9 @@ public void register() {
 
                 handler(wrapper -> {
                     EntityTracker1_9 tracker = wrapper.user().getEntityTracker(Protocol1_8To1_9.class);
-                    tracker.setGameMode(GameMode.getById(wrapper.get(Types.UNSIGNED_BYTE, 0))); //Set player gamemode
+                    short gamemodeId = wrapper.get(Types.UNSIGNED_BYTE, 0);
+                    gamemodeId &= -9; // remove the hardcore mode flag
+                    tracker.setGameMode(GameMode.getById(gamemodeId)); //Set player gamemode
                 });
 
                 // Track player's dimension