cleanup player death event adventure logic (#10095)

There was a TODO left there regarding the translated death
message being used by plugins to identify the cause of death. This
should be mitigated now because the LegacyComponentSerializer default
implemenation uses our custom flattener which renders vanilla
translatable components to their English representation.

patches/server/Improve-death-events.patch

@@ -45,7 +45,7 @@ index 0000000000000000000000000000000000000000..00000000000000000000000000000000
 @@ -0,0 +0,0 @@ public class ServerPlayer extends Player {
          String deathmessage = defaultMessage.getString();
          this.keepLevel = keepInventory; // SPIGOT-2222: pre-set keepLevel
-         org.bukkit.event.entity.PlayerDeathEvent event = CraftEventFactory.callPlayerDeathEvent(this, loot, PaperAdventure.asAdventure(defaultMessage), defaultMessage.getString(), keepInventory); // Paper - Adventure
+         org.bukkit.event.entity.PlayerDeathEvent event = CraftEventFactory.callPlayerDeathEvent(this, loot, PaperAdventure.asAdventure(defaultMessage), keepInventory); // Paper - Adventure
 +        // Paper start - cancellable death event
 +        if (event.isCancelled()) {
 +            // make compatible with plugins that might have already set the health in an event listener
@@ -443,7 +443,7 @@ index 0000000000000000000000000000000000000000..00000000000000000000000000000000
  
          for (org.bukkit.inventory.ItemStack stack : event.getDrops()) {
 @@ -0,0 +0,0 @@ public class CraftEventFactory {
-         PlayerDeathEvent event = new PlayerDeathEvent(entity, drops, victim.getExpReward(), 0, deathMessage, stringDeathMessage); // Paper - Adventure
+         PlayerDeathEvent event = new PlayerDeathEvent(entity, drops, victim.getExpReward(), 0, deathMessage);
          event.setKeepInventory(keepInventory);
          event.setKeepLevel(victim.keepLevel); // SPIGOT-2222: pre-set keepLevel
 +        populateFields(victim, event); // Paper - make cancellable