SAST Vulnerability Resolution - Rename created custom ability to make it more generic.

What does this MR do and why?

We created custom ability update_sast_vr_setting in #599602 (closed) (see: !235831 (merged)). In this MR we are renaming update_sast_vr_setting to update_sec_ai_workflow_settings because eventually want to have the same ability for all AI workflows (from sec), and making the name more generic now to be re-used in the future will safe us work eventually.

We are renaming:

• Permission: update_sast_vulnerability_resolution_setting → update_sec_ai_workflow_settings
• Custom ability YAML, permission config directory, and all related internal method names and constants updated to match

Not renamed:

• feature flag update_sast_vr_setting_permission (separate concern)

Closes: #601502 (closed)

References

• Main epic: SAST Vulnerability Resolution – Permission AppS... (gitlab-org#21725) • Charlie Kroon • 19.1
  • Backend epic: SAST Vulnerability Resolution - Backend (gitlab-org#21971) • Charlie Kroon
  • Relevant discussion where we decided to make a generic name: gitlab-org#21725 (comment 3324237411)
  • MR where custom ability was initially created: #599602 (closed) (see: !235831 (merged))

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