Remove fallback for old non-convoy behavior.

game/settings.py

@@ -37,11 +37,6 @@ class Settings:
     disable_legacy_aewc: bool = False
     generate_dark_kneeboard: bool = False
 
-    #: Feature flag for new ground unit behavior. Old campaigns are will not work with
-    #: this so the old behavior remains an option until it breaks, at which point we'll
-    #: remove it.
-    enable_new_ground_unit_recruitment: bool = True
-
     # Performance oriented
     perf_red_alert_state: bool = True
     perf_smoke_gen: bool = True