Quarantined Outpost tweaks and bugfixes (#21586)

## About PR

- Reduces the site's cost from `2` to `1`.
- Tweaks wall destroying logic of horde type mobs to a saner
alternative.
- Fixes corpses created by landmarks not getting assigned with the
specified access. Fixes #21527
- Creates an abomination subtype that is guaranteed to spawn with a
disguise.

code/modules/awaymissions/corpse.dm

@@ -107,7 +107,7 @@
 				if(jobdatum)
 					W.access = jobdatum.get_access()
 				else
-					W.access = list()
+					W.access = corpseidaccess
 			if(corpseidjob)
 				W.assignment = corpseidjob
 			M.set_id_info(W)