Metagame improvements to antag-before-job selection system (#35830)

* Initial commit

* Update the selection to only count for people who have one of the preferences assigned; latejoin on delay no longer applies pre-selection.

Resources/Prototypes/GameRules/roundstart.yml

@@ -34,6 +34,15 @@
     - id: Thief
       prob: 0.5
 
+- type: entity
+  parent: BaseGameRule
+  id: DummyNonAntagChance
+  components:
+  - type: SubGamemodes
+    rules:
+    - id: DummyNonAntag
+      prob: 0.3
+
 - type: entity
   id: DeathMatch31
   parent: BaseGameRule
@@ -333,6 +342,22 @@
       mindRoles:
       - MindRoleInitialInfected
 
+# This rule makes the chosen players unable to get other antag rules, as a way to prevent metagaming job rolls.
+# Put this before antags assigned to station jobs, but after non-job antags (NukeOps/Wiz).
+- type: entity
+  id: DummyNonAntag
+  parent: BaseGameRule
+  components:
+  - type: GameRule
+    minPlayers: 5
+  - type: AntagSelection
+    selectionTime: IntraPlayerSpawn # Pre-selection before jobs; assignment doesn't really matter though, we only care about the pre-selection to block other antags.
+    removeUponFailedSpawn: false
+    definitions:
+    - prefRoles: [ InitialInfected, Traitor, Thief, HeadRev ]
+      max: 2
+      playerRatio: 30
+
 # event schedulers
 
 - type: entityTable