Change search specs codeowners to optional

What does this MR do and why?

Change the migration specs to be optional after discussion in !140631 (comment 1707488608)

We should not block specs quarantine or fixes if none of the team is available.

Note: I left the elastic spec support file because that file impacts all specs that use the elastic* traits. Changes to it should be reviewed by a person from groupglobal search

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

CODEOWNERS only change

How to set up and validate locally

N/A