Improve logging for 401 errors when installing the Jira Cloud app with the app descriptor

Proposal

Following https://gitlab.slack.com/archives/C04RDL3MEH5/p1709596348275439, when installing the GitLab for Jira Cloud app via the manual app descriptor method it is possible that you will see a 401 error on the POST /-/jira_connect/events/installed endpoint and the install fails with:

The app host returned HTTP response code 401 when we tried to contact it during installation. Please try again later or contact the app vendor.

We are currently looking at this troubleshooting doc and the source code and it seems the only place the 401 would be triggered is in Atlassian::JiraConnect::Jwt::Asymmetric if an exception is triggered. I'm thinking we should add a logger to the rescue to see if we can get more details if and when a 401 is triggered here.

This could greatly help customers and Support troubleshoot any errors that are captured by this rescue statement.

This is one example of how the rescue could be modified (any exceptions would be logged to exceptions_json.log:

rescue JWT::DecodeError, OpenSSL::PKey::PKeyError, KeyFetchError => e
  Gitlab::ErrorTracking.track_exception(e)
  nil
end

This will likely need to be reviewed by Application Security to ensure nothing sensitive is leaked here.