Revert "Fix non-matching defaults in docs (#5446) (#5451)"

This reverts commit b26df2a008.

plugins/modules/files/iso_customize.py

@@ -40,7 +40,6 @@ options:
     type: list
     required: false
     elements: str
-    default: []
   add_files:
     description:
     - Allows to add and replace files in the ISO file.
@@ -48,7 +47,6 @@ options:
     type: list
     required: false
     elements: dict
-    default: []
     suboptions:
       src_file:
         description:

plugins/modules/files/xml.py

@@ -40,7 +40,6 @@ options:
     - The namespace C(prefix:uri) mapping for the XPath expression.
     - Needs to be a C(dict), not a C(list) of items.
     type: dict
-    default: {}
   state:
     description:
     - Set or remove an xpath selection (node(s), attribute(s)).