redhat_subscription: stop manual unsubscribing on unregistration

Unregistering a system also drops all the resources for it
automatically, so there is no need to manually unsubscribing (which
actually means removing all the subscriptions).

In addition to that, newer versions of subscription-manager drop all the
support for entitlements, so the "remove" subcommand (used by
unsubscribe()) does not exist anymore, and thus the unregistration fails
with those versions.

This fixes the registration on EL 10 systems, and Fedora 41 and greater.

changelogs/fragments/9578-redhat_subscription-no-remove-on-unregister.yml

@@ -0,0 +1,7 @@
+bugfixes:
+  - |
+    redhat_subscription - do not try to unsubscribe (i.e. remove subscriptions)
+    when unregistering a system: newer versions of subscription-manager, as
+    available in EL 10 and Fedora 41+, do not support entitlements anymore, and
+    thus unsubscribing will fail
+    (https://github.com/ansible-collections/community.general/pull/9578).

plugins/modules/redhat_subscription.py

@@ -1119,7 +1119,6 @@ def main():
             module.exit_json(changed=False, msg="System already unregistered.")
         else:
             try:
-                rhsm.unsubscribe()
                 rhsm.unregister()
             except Exception as e:
                 module.fail_json(msg="Failed to unregister: %s" % to_native(e))

tests/unit/plugins/modules/test_redhat_subscription.py

@@ -199,11 +199,6 @@ def test_without_required_parameters_registered(mocker, capfd, patch_redhat_subs
                     {'check_rc': False},
                     (0, 'system identity: b26df632-25ed-4452-8f89-0308bfd167cb', '')
                 ),
-                (
-                    ['/testbin/subscription-manager', 'remove', '--all'],
-                    {'check_rc': True},
-                    (0, '', '')
-                ),
                 (
                     ['/testbin/subscription-manager', 'unregister'],
                     {'check_rc': True},