Update ansible-test integration tests. (#69970)

* Extend ansible-test collection test.

It now runs `rstcheck` and `empty-init` tests.

* Add galaxy.yml to test collections.

test/integration/targets/ansible-test-docker/ansible_collections/ns/col/galaxy.yml

@@ -0,0 +1,6 @@
+namespace: ns
+name: col
+version: 1.0.0
+readme: README.rst
+authors:
+    - Ansible

test/integration/targets/ansible-test/ansible_collections/ns/col/README.rst

@@ -0,0 +1,3 @@
+README
+------
+This is a simple collection used to verify that ``ansible-test`` works on a collection.

test/integration/targets/ansible-test/ansible_collections/ns/col/galaxy.yml

@@ -0,0 +1,6 @@
+namespace: ns
+name: col
+version: 1.0.0
+readme: README.rst
+authors:
+    - Ansible