[os_foundation/metalos] use antlir2 scratch images for everything

Summary:
This fbpkg is always very out of date.

I'll keep cleaning up these directories and eventually move it to `metalos/`
but smaller diffs are easier to review :)

NOTE: this is basically a no-op since all the antlir2 images (what is actually going out to production) already use these targets and not the `metalos.base` fbpkg.

Test Plan: waitforsandcastle

Reviewed By: epilatow

Differential Revision: D49827733

fbshipit-source-id: 469bcf21a764581c2e281e575d5f2583c189d89d

antlir/antlir2/antlir1_compat/antlir1_compat.bzl

@@ -24,6 +24,8 @@ load("//antlir/bzl/image/feature:defs.bzl", "feature")
 _ALLOWED_LABELS = (
     "fbcode//antlir/antlir2/antlir1_compat/tests:antlir1-layer",
     "fbcode//metalos/os/vm:rootfs.antlir1",
+    "fbcode//os_foundation/metalos/impl/centos8:basesystem.rc.antlir1",
+    "fbcode//os_foundation/metalos/impl/centos9:basesystem.rc.antlir1",
 )
 
 _ALLOWED_PACKAGES = (