[collection] remove module defaults where API defaults are the same (#13037)

Providing defaults for API parameters where the API already provides
defaults leads to some confusing scenarios, because we end up always
sending those collection-defaulted fields in the request even if the
field isn't provided by the user.

For example, we previously set the `scm_type` default to 'manual' and
someone using the collection to update a project who does not explicitly
include the `scm_type` every time they call the module, would
inadvertently change the `scm_type` of the project back to 'manual'
which is surprising behavior.

This change removes the collection defaults for API parameters, unless
they differed from the API default. We let the API handle the defaults
or otherwise ignore fields not given by the user so that the user does
not end up changing unexpected fields when they use a module.

Signed-off-by: Rick Elrod <rick@elrod.me>

awx_collection/plugins/modules/subscriptions.py

@@ -17,7 +17,7 @@ module: subscriptions
 author: "John Westcott IV (@john-westcott-iv)"
 short_description: Get subscription list
 description:
-    - Get subscriptions available to  Automation Platform Controller. See
+    - Get subscriptions available to Automation Platform Controller. See
       U(https://www.ansible.com/tower) for an overview.
 options:
     username: