GraphQL: Deprecate RunnerMembershipFilter

What does this MR do and why?

Describe in detail what your merge request does and why.

This MR fixes a typo in the GraphQL type name RunnerMembershipFilter by renaming it to CiRunnerMembershipFilter and adding a type forwarding from RunnerMembershipFilter->CiRunnerMembershipFilter.

I've added a Changelog: deprecated trailer even though there isn't a real deprecation issue, since that seems to be the way previous GlobalID deprecations were handled.

Part of Group runners should display all runners availa... (#337838 - closed)

Screenshots or screen recordings

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type	screenshot
CiRunnerMembershipFilter
RunnerMembershipFilter

How to set up and validate locally

Numbered steps to set up and validate the change are strongly suggested.

1. Visit http://gdk.test:3000/-/graphql-explorer

2. Enter the following JSON in the Query Variables window:

   {
     "membership": "DESCENDANTS"
   }

3. Enter the following GraphQL query:

   query getRunners($membership: RunnerMembershipFilter) {
     group(fullPath: "gitlab-org") {
       runners(membership: $membership) {
         nodes {
           id
         }
       }
     }
   }

4. Replace the GraphQL query with:

   query getRunners($membership: CiRunnerMembershipFilter) {
     group(fullPath: "gitlab-org") {
       runners(membership: $membership) {
         nodes {
           id
         }
       }
     }
   }

The query should work both times without complaining about the deprecated RunnerMembershipFilter type name.

MR acceptance checklist

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