Clean up module documentation (#36909)

* Clean up module documentation

This PR includes:
- Removal of `default: None` (and variations)
- Removal of `required: false`
- Fixing booleans and `type: bool` where required

* Fix remaining (new) validation issues

lib/ansible/utils/module_docs_fragments/validate.py

@@ -22,10 +22,8 @@ class ModuleDocFragment(object):
     DOCUMENTATION = '''
 options:
     validate:
-      required: false
       description:
        - The validation command to run before copying into place. The path to the file to
          validate is passed in via '%s' which must be present as in the example below.
          The command is passed securely so shell features like expansion and pipes won't work.
-      default: None
 '''