Add manual install troubleshooting to Jira connect app documentation

What does this MR do and why?

This adds a manual installation troubleshooting section to the Jira connect app documentation.

Related issues:

• #386827 (closed)
• #387520 (closed)

How to set up and validate locally

1. Visit http://127.0.0.1:3000/help/integration/jira/connect-app.html#troubleshoot-gitlabcom-for-jira-cloud-app

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 #386827 (closed)