Vagueifies the group templates count for performance

What does this MR do and why?

Removes the accuracy of the group templates count when the :project_templates_without_min_access feature flag is enabled. It now shows only an indicator that there is more than 1 template, or 0. This resolves a major performance problem caused by checking permissions for hundreds of group template projects in a loop until we can heavily rework some of the auth code to be more performant.

Related #441462

This is related to the following rollout: #425452 (closed). The rollout of this feature is more important than accurate counters. However the queries this skips may then be executed again by the code used to show the list, so it's unclear yet as to whether this fully resolves the issue.

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