Draft: Change loading icon to skeleton loader for pipeline details header

What does this MR do and why?

Change loading icon to skeleton loader for pipeline details header

Change the loading icon for pipeline header to a skeleton loader.

Changelog: changed

MR acceptance checklist

Please evaluate this MR against the MR acceptance checklist. It helps you analyze changes to reduce risks in quality, performance, reliability, security, and maintainability.

Screenshots or screen recordings

How to set up and validate locally

1. Visit Build > Pipelines > Single pipeline
2. View pipeline details header section

Related to #450852