Improve handling of integration test aliases. (#38698)

* Include change classification data in metadata.
* Add support for disabled tests.
* Add support for unstable tests.
* Add support for unsupported tests.
* Overhaul integration aliases sanity test.
* Update Shippable scripts to handle unstable tests.
* Mark unstable Azure tests.
* Mark unstable Windows tests.
* Mark disabled tests.

test/utils/shippable/shippable.sh

@@ -53,6 +53,14 @@ else
     export CHANGED="--changed"
 fi
 
+if [ "${IS_PULL_REQUEST:-}" == "true" ]; then
+    # run unstable tests which are targeted by focused changes on PRs
+    export UNSTABLE="--allow-unstable-changed"
+else
+    # do not run unstable tests outside PRs
+    export UNSTABLE=""
+fi
+
 # remove empty core/extras module directories from PRs created prior to the repo-merge
 find lib/ansible/modules -type d -empty -print -delete