Make some Soviet actors buildable in exodus

Their Allied counter-parts are already buildable.
Arty is still excluded on purpose.

mods/ra/maps/exodus/rules.yaml

@@ -39,10 +39,6 @@ E7:
 	Buildable:
 		Prerequisites: ~disabled
 
-BARR:
-	Buildable:
-		Prerequisites: ~disabled
-
 MIG:
 	Buildable:
 		Prerequisites: ~disabled
@@ -75,14 +71,6 @@ PDOX:
 	Buildable:
 		Prerequisites: ~disabled
 
-TSLA:
-	Buildable:
-		Prerequisites: ~disabled
-
-FTUR:
-	Buildable:
-		Prerequisites: ~disabled
-
 SAM:
 	Buildable:
 		Prerequisites: ~disabled
@@ -111,10 +99,6 @@ MCV:
 	Buildable:
 		Prerequisites: ~disabled
 
-APC:
-	Buildable:
-		Prerequisites: ~disabled
-
 MNLY:
 	Buildable:
 		Prerequisites: ~disabled
@@ -127,10 +111,6 @@ TTNK:
 	Buildable:
 		Prerequisites: ~disabled
 
-FTRK:
-	Buildable:
-		Prerequisites: ~disabled
-
 CTNK:
 	Buildable:
 		Prerequisites: ~disabled