Consolidate 'vertex_ai_proxy' UP usage and ensure service mapping for relevant UPs

Everyone can contribute. Help move this issue forward while earning points, leveling up and collecting rewards.

• Collaborate/take over this issue

To proceed with the Refactor AiGateway.headers to accept unit_primitive and use pass it to Tokens.get issue, we need to ensure that every Unit Primitive that is explicitly used from permission checks has corresponding service with the same name (either defined explicitly in CC library config or virtually through AvailableServicesGenerator).

We tackle this in steps.

This issue is dedicated to UPs used in vertex_ai_proxy service/endpoint. Anthropic issue is here.

Currently, vertex_ai_proxy service lists these UPs:

UP name	In use?	References in code/logs	Action
generate_commit_message	✅	groupcode creation GA feature (Beta for SHM) Does not appear in AIGW logs	Update owner in UP YAML
generate_cube_query	⛔	VertexAi::Completions groupproduct analytics behind an old FF that is enabled only for select .com groups Does not appear in AIGW logs	Confirmed that this can be removed as it is not used, and there is an open MR to remove the client code.
glab_ask_git_command	✅	groupcode review GA feature (Beta for SHM) Does not appear in AIGW logs	No action
semantic_search_issue	✅	groupglobal search Text embeddings for issue search Appears in AIGW logs	Remove from IGNORE_UNIT_PRIMITIVES
summarize_issue_discussions	❓	groupcode review Only reference in code is in Completions::SummarizeAllOpenNotes, but this uses the Anthropic::Client not VertexAI Does not appear in AIGW logs	Check with code owner if this can be deleted from vertex_ai_proxy service

We need to carefully review the usage of the listed UPs and for each of them:

• Either remove it entirely from the linked service yml definition
• Or, if they are still used, remove them from https://gitlab.com/gitlab-org/cloud-connector/gitlab-cloud-connector/-/blob/main/src/ruby/lib/gitlab/cloud_connector/available_services_generator.rb#L11 IGNORE_UNIT_PRIMITIVES to make sure we have 1:1 mapping with the service

We should grep the codebase and use the logs from AI GW - https://log.gprd.gitlab.net/app/r/s/rdiwc - to understand the usage.

For safety, we need to wait until 18.2 final version is released before bumping the library (as it can be picked up by renovate and we can introduce the regression if there is a problem with the change).

We will use the table to receive approval from stakeholders and for transparency during the rollout.