Validate modules arg spec fixes (#34477)

* Update validate-modules arg_spec introspection to be faster, by only mocking the imports we explicitly list
* The use of types.MethodType in redhat_subscription wasn't py3 compatible, use partial instead
* Remove argument_spec import hacks, make them errors, we can ignore them with ansible-test
* Enable the --arg-spec flag for validate-modules

test/runner/lib/sanity/validate_modules.py

@@ -57,6 +57,7 @@ class ValidateModulesTest(SanitySingleVersion):
             'python%s' % args.python_version,
             'test/sanity/validate-modules/validate-modules',
             '--format', 'json',
+            '--arg-spec',
         ] + paths
 
         with open(VALIDATE_SKIP_PATH, 'r') as skip_fd: