Use default timeouts for Jira calls

What does this MR do and why?

This MR changes external calls to Jira to use the default Gitlab::HTTP timeout values. Previously the read_timeout value was set at 120 (which became the timeout when passed to Gitlab::HTTP).

See: https://gitlab.com/gitlab-org/gitlab/-/issues/343174 (and https://gitlab.com/gitlab-com/gl-infra/production/-/issues/5732#note_705356799)

How to set up and validate locally

Numbered steps to set up and validate the change are strongly suggested.

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 #343174