Cleanup: move VINTF fragments into VAPEX

VINTF fragments for Power VAPEX were installed in /vendor/etc as a
workaround when VINTF fragments in VAPEX were not supported.

Bug: n/a
Test: m && launch_cvd
      # power/power-stat services are running
Change-Id: I0243a0bd2f2dd597260f73a3994cf81db213daf7
diff --git a/power/aidl/default/Android.bp b/power/aidl/default/Android.bp
index da91ee6..64766fc 100644
--- a/power/aidl/default/Android.bp
+++ b/power/aidl/default/Android.bp
@@ -39,9 +39,11 @@
     ],
 }
 
-filegroup {
+prebuilt_etc {
     name: "android.hardware.power.xml",
-    srcs: ["power-default.xml"],
+    src: "power-default.xml",
+    sub_dir: "vintf",
+    installable: false,
 }
 
 filegroup {