Trim leading and trailing whitespace from Jira username upon save

What does this MR do?

If leading or trailing whitespace exists for the supplied username for the jira integration, trim it before saving

Are there points in the code the reviewer needs to double check?

Trim the whitespace or validate against it? I think it's safe to trim and guard against an invalid value being supplied.

Why was this MR needed?

Can lead to confusion if usernames with spaces are persisted and the Jira configuration does not work because of this

Screenshots (if relevant)

Does this MR meet the acceptance criteria?

• Changelog entry added, if necessary
• Documentation created/updated
• API support added
• Tests added for this feature/bug
• Review
  • Has been reviewed by UX
  • Has been reviewed by Frontend
  • Has been reviewed by Backend
  • Has been reviewed by Database
• Conform by the merge request performance guides
• Conform by the style guides
• Squashed related commits together

What are the relevant issue numbers?

Closes #36495