Remove unused gate sequences.

The artwork no longer exists, so these cause
errors to be written to debug.log.

mods/ra/sequences/structures.yaml

@@ -619,33 +619,6 @@ brik:
 		Length: 16
 	icon: brikicon
 
-vgate:
-	make:
-		Length: 7
-	idle:
-		Frames: 6, 5, 4, 3, 2, 1, 0
-		Length: 7
-		ZOffset: -1c511
-	damaged-idle:
-		Frames: 13, 12, 11, 10, 9, 8, 7
-		Length: 7
-		ZOffset: -1c511
-
-agate:
-	make:
-		Length: 7
-	idle:
-		Frames: 6, 5, 4, 3, 2, 1, 0
-		Length: 7
-		ZOffset: -1c511
-	damaged-idle:
-		Frames: 13, 12, 11, 10, 9, 8, 7
-		Length: 7
-		ZOffset: -1c511
-
-sgate:
-	Inherits: agate
-
 sbag:
 	idle:
 		Length: 16