🧪⇪ Bump `galaxy_ng` to v4.9.0 in tests

It updates the underlying `pulp_ansible` to v0.20.2, which fixes a
race condition that is occasionally observable in our CI when
provisioning the initial dummy collections for testing.

Refs:

  * https://github.com/ansible/galaxy_ng/releases/tag/4.9.0
  * https://github.com/ansible/galaxy_ng/pull/1950
  * https://github.com/ansible/galaxy/issues/3267
  * https://github.com/pulp/pulp_ansible/issues/1571
  * https://github.com/pulp/pulp_ansible/pull/1572
  * https://github.com/pulp/pulp_ansible/pull/1595
  * https://github.com/pulp/pulp_ansible/issues/1623
  * https://github.com/pulp/pulp_ansible/pull/1624

test/lib/ansible_test/_internal/commands/integration/cloud/galaxy.py

@@ -98,7 +98,7 @@ class GalaxyProvider(CloudProvider):
 
         self.image = os.environ.get(
             'ANSIBLE_PULP_CONTAINER',
-            'quay.io/pulp/galaxy:4.7.1'
+            'quay.io/pulp/galaxy:4.9.0'  # https://github.com/ansible/galaxy_ng
         )
 
         self.uses_docker = True