Add create_merge_request_pipeline MCP tool

Pavan Kumar Sadashivrequested to merge
gitlab-community/gitlab-org/gitlab:hrlpavan-604238-mcp-create-mr-pipeline into master

What does this MR do and why?

Exposes POST /projects/:id/merge_requests/:merge_request_iid/pipelines as the create_merge_request_pipeline MCP tool in the :merge_requests toolset so MCP clients and agents can trigger pipelines properly associated with a merge request instead of creating detached ref pipelines.

  • Adds requires :merge_request_iid, type: Integer and route_setting :mcp (tool_name: :create_merge_request_pipeline, toolset: :merge_requests, params: [:id, :merge_request_iid, :async]) on POST ':id/merge_requests/:merge_request_iid/pipelines'.
  • Updates SavePipelineService description to direct callers to create_merge_request_pipeline when creating a pipeline linked to a merge request.

Closes #604238

Merge request reports