Properly check water block when random ticking ice (#9804)

Readds a lost update to the shared mutable state in the random block
ticking optimisation.

patches/server/Optimise-random-block-ticking.patch

@@ -202,6 +202,7 @@ index 0000000000000000000000000000000000000000..00000000000000000000000000000000
  
 -        if (biomebase.shouldFreeze(this, blockposition2)) {
 -            org.bukkit.craftbukkit.event.CraftEventFactory.handleBlockFormEvent(this, blockposition2, Blocks.ICE.defaultBlockState(), null); // CraftBukkit
++        blockposition1.setY(downY);
 +        if (biomebase.shouldFreeze(this, blockposition1)) {
 +            org.bukkit.craftbukkit.event.CraftEventFactory.handleBlockFormEvent(this, blockposition1, Blocks.ICE.defaultBlockState(), null); // CraftBukkit
          }