Remove views.view.group_pending_members override from SocialGroupRequestConfigOverride and move it to config/optional

Problem/Motivation

In issue https://www.drupal.org/project/social/issues/3453509 → we discussed removing the insert hook, but before doing that we need to remove any reference to that field. One reference is in the SocialGroupRequestConfigOverride.php where we add the override and add the field to the view. We need to get rid of that and instead of the override we need to move the config to config/optional folder.

Steps to reproduce

Proposed resolution

Remove the override and move the config to config/optional folder.

Remaining tasks

User interface changes

API changes

Data model changes