Include *.jira.com in Jira Connect CSP frame ancestors

What does this MR do and why?

This is needed for some legacy Jira Cloud instances, new ones will use *.atlassian.net domains.

Fixes #337033 (closed)

How to set up and validate locally

We can't fully validate this since we'd need a Jira Cloud instance with a *.jira.com domain, so I only checked that the CSP syntax is correct:

• https://developer.mozilla.org/en-US/docs/Web/HTTP/Headers/Content-Security-Policy/frame-ancestors

• https://csp-evaluator.withgoogle.com/

  

MR acceptance checklist

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