Revert "Merge branch '228646-filter-epics-pill-count-by-visibility' into 'master'"

What does this MR do and why?

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This change created availability issues primarily for customers that use SAML SSO and have large numbers of subgroups under a single top-level group. It also puts pressure on downstream services.

See #355151 (closed).

Reverting will return a minor security issue (#228646 (closed)) that was public and fixed in the regular development workflow. However, this can be rescheduled with a new fix and the availability issue is of higher severity.

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