"Existing shares" number on members page is misleading

Summary

The "Existing shares" number displayed on a group's members page only counts the users displayed on that page (max 50), rather than the actual total.

Steps to reproduce

Have more than 50 members in a group, then look at the group_members page.

What is the current bug behavior?

Group has a member count of 65, for example. Page 1 of members shows "Existing shares" as 50. Page 2 of members shows "Existing shares" as 15.

What is the expected correct behavior?

"Existing shares" should be consistent, showing the actual total number of members (that match the given filter).

Output of checks

This bug happens on GitLab.com