GraphQL: Rename RunnerMembershipFilter to CiRunnerMembershipFilter

🚨🚨 NOTE: This MR should only be merged on Apr 22nd, in time for the 1st breaking changes window (2024-04-22 09:00 UTC to 2024-04-24 22:00 UTC) 🚨🚨

What does this MR do and why?

This MR renames the GraphQL RunnerMembershipFilter to CiRunnerMembershipFilter. The rename actually was already in place, but this MR removes the alias that was in place.

Changelog: changed

Part of #409333 (closed)

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