Fix treble sepolicy tests and combine_maps script

* Since vFRC there are no more minor version, so combine_maps.py is
  fixed to correctly handle both vFRC version and prior V.v version.

* treble_sepolicy_tests_for_release.mk uses incorrect variable
  SYSTEM_EXT_PREBUILT_POLICY and PRODUCT_PREBUILT_POLICY, so fixing
  them.

Bug: 331866470
Test: m selinux_policy
Change-Id: I7a3ab7cf3abf2155c1998e1972adee1202af8dff
diff --git a/tests/combine_maps.py b/tests/combine_maps.py
index 1a7dfaa..b0fb850 100644
--- a/tests/combine_maps.py
+++ b/tests/combine_maps.py
@@ -41,8 +41,9 @@
         if len(top_type_set) == 1:
             continue
 
-        m = re.match(r"(\w+)_\d+_\d+", top_ta)
-        # Typeattributes in V.v.cil have _V_v suffix, but not in V.v.ignore.cil
+        m = re.fullmatch(r"(\w+?)_\d+(_0)?", top_ta)
+        # Typeattributes in V(.0).cil have _V(_0) suffix, but not in
+        # V(.0).ignore.cil
         bottom_type = m.group(1) if m else top_ta
 
         # If type doesn't exist in bottom map, no need to maintain mappings to