gating.yaml: duplicate the stanzas

The Gating spec[1] used to recommend having one type of
YAML stanza for master, one for released branches. We
just discovered today that this breaks when master
forks into a release branch: the string 'stable'
needs to be manually changed to 'testing', and
nobody is going to remember to do that, and I can't
think of a (non-tedious) way to add automated checks.

As of 2019-08 (09d7d4f), though, the Gating spec suggests
having *both* stanzas together in the same gating.yaml
file. @pingou himself concurs[2]. Although this is
horrible duplication -- two hundred characters, repeated
with only six of those different -- it seems cleaner
than the maintenance burden of having to update
release branches.

 [1] https://docs.fedoraproject.org/en-US/ci/gating/
 [2] https://src.fedoraproject.org/rpms/podman/pull-request/33

Oh, also, add a new 'subject_type' line apparently "required"
even though things seem to have been working fine without it.
(Source: same commit, 09d7d4f, on gating.adoc).

Signed-off-by: Ed Santiago <santiago@redhat.com>

gating.yaml

@@ -2,5 +2,13 @@
 product_versions:
   - fedora-*
 decision_context: bodhi_update_push_stable
+subject_type: koji_build
+rules:
+  - !PassingTestCaseRule {test_case_name: fedora-ci.koji-build.tier0.functional}
+--- !Policy
+product_versions:
+  - fedora-*
+decision_context: bodhi_update_push_testing
+subject_type: koji_build
 rules:
   - !PassingTestCaseRule {test_case_name: fedora-ci.koji-build.tier0.functional}