Part 1 - Migrate pipeline editor PMG to GraphQL instance

What does this MR do and why?

This MR is part 1 for #466275 (closed).

The main purpose is to consolidate pipeline queries.

• Consolidate get_pipeline_metadata and get_pipeline_mini_graph into 1 query, get_pipeline_summary
• Switch off the pipeline editor and MR widget feature flags so that only <pipeline-summary> uses <pipeline-mini-graph>
• Update <pipeline-mini-graph> to take in data and use query/polling logic in <pipeline-summary>

NOTE: The diff looks a lot larger than it is and there are no logic updates. pipeline_mini_graph.vue has been drastically simplified now that pipeline_summary.vue passes in stages, upstream, and downstream.

The feature flag references were removed from the merge request widget as we have changed trajectory to just do a component migration as a whole coming up. Since pipelines tables must pass data in and the only other component which will use pmg is <pipeline-summary>, we are shifting to have the pipeline mini graph take in data. This MR has only enough code removed to insure that <pipeline-mini-graph> is only called by <pipeline-summary>. More removals coming up.

Coming up:

• Part 2: Update pipeline editor page to use <pipeline-summary>: Part 2 - Migrate pipeline editor PMG to GraphQL (!175179 - merged)
• Part 3: Remove dead pipeline editor code: Part 3 - Migrate pipeline editor PMG to GraphQL (!175334 - merged)

In the future we will also update the merge request widget to use <pipeline-summary>

Screenshots or screen recordings

Before	After

How to set up and validate locally

1. In a project with pipelines, navigate to a commit (http://gdk.test:3000/flightjs/Flight/-/commit/<commit-id>)
2. Verify that the pipeline is rendered from 1 query and not 2