Allow delete runners in bulk in group runner page

What does this MR do and why?

This MR depends on !102521 (merged).

This change enables users to deleted multiple runners at the same time by selecting them from the group runners page.

Adds documentation for group runners bulk delete

Changelog: added

Screenshots or screen recordings

How to set up and validate locally

NA

MR acceptance checklist

This checklist encourages us to confirm any changes have been analyzed to reduce risks in quality, performance, reliability, security, and maintainability.

• I have evaluated the MR acceptance checklist for this MR.

Related to #361721 (closed)