Fixed `members/all` subgroup inherited members return

What does this MR do and why?

Updated members/all API to also return "inherited-shared-groups" users, on subgroups.
This Mr also fixes /-/group_members WebUI to correctly show inherited-shared-members.
This MR is bug has been reported on #321694 (comment 826392640), by @pierrefevrier, thanks for finding this.
Fixes: #321694 (closed)
Fixes: #214741 (closed)

Screenshots or screen recordings

Subgroup members WebUI before and after fix.

Before:
After:

SQL Query

SQL

group = Group.find(9970)
finder = GroupMembersFinder
           .new(group)
           .execute(include_relations: [:shared_from_groups])

SELECT 
  "members".* 
FROM 
  (
    SELECT 
      DISTINCT ON (user_id, invite_email) * 
    FROM 
      "members" 
    WHERE 
      "members"."type" = 'GroupMember' 
      AND "members"."source_type" = 'Namespace' 
      AND "members"."requested_at" IS NULL 
      AND "members"."source_id" IN (
        SELECT 
          "namespaces"."id" 
        FROM 
          "namespaces" 
          INNER JOIN "group_group_links" ON "group_group_links"."shared_with_group_id" = "namespaces"."id" 
        WHERE 
          "namespaces"."type" = 'Group' 
          AND "group_group_links"."shared_group_id" IN (
            SELECT 
              "namespaces"."id" 
            FROM 
              "namespaces" 
            WHERE 
              "namespaces"."type" = 'Group' 
              AND "namespaces"."id" = 9970
          )
      ) 
      AND (members.access_level > 5) 
    ORDER BY 
      user_id, 
      invite_email, 
      access_level DESC, 
      expires_at DESC, 
      created_at ASC
  ) members 
WHERE 
  "members"."type" = 'GroupMember'

https://postgres.ai/console/gitlab/gitlab-production-tunnel-pg12/sessions/11053/commands/39597

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