Revert changes to ENCOUNTER_END

Initial changeset would change loot spec back to default when the ENCOUNTER_ENDs.
This lead to confusing behavior of the addon.
Reverting this change means that the loot spec will not change back to the default setting.

LootSpecManager/LootSpecManager.lua

@@ -142,13 +142,6 @@ function events:ENCOUNTER_START(id, _, difficulty)
   end
 end
 
-function events:ENCOUNTER_END()
-  if C_ChallengeMode.GetActiveKeystoneInfo() ~= 0 then
-    return
-  end
-  set_spec(LTSM_API:get_default_spec())
-end
-
 function events:CHALLENGE_MODE_START(mapId)
   if set_spec(LTSM_API:get_mythicplus_spec(mapId)) then
     print("[LTSM] M+ started, loot spec changed.")