Pipeline Authoring - Pipeline performance improvements
## Overview
This epic represents a collection of issues to improve the performance of areas related to the pipeline codebase that ~"group::pipeline authoring" supports.
## Why is this important to the business?
With the amount of users that we support, it is important that the features that we provide perform well and can scale in the future.
## Data analysis to support this prioritization
In https://gitlab.com/gitlab-org/gitlab/-/issues/324767, improving the performance by 10x will happen by changing to use `set` instead of `array`
```
user system total real
array 0.000203 0.000002 0.000205 ( 0.000203)
set 0.000024 0.000000 0.000024 ( 0.000025)
```
In https://gitlab.com/gitlab-org/gitlab/-/issues/392707, by analyzing how to pare down 100 queries, this could improve the page load performance from around 5s to 3s. A 40% improvement.
epic