Fix subpath in jira issue list feature

What does this MR do?

The Jira client doesn't automatically add a sub-path when executing custom requests. This leads to an error message when loading the issue list like described in #288019 (closed)

Steps to reproduce

1. Configure a Jira instance with an alternate context path. Like `http://jira.example.com/subpath-to-jira
2. Configure the Jira integration on a GitLab project.
3. Go to /project-path/-/integrations/jira/issues

Related issues

• #244354 (closed)
• #288019 (closed)

Screenshots (strongly suggested)

Does this MR meet the acceptance criteria?

Conformity

• Changelog entry
• [-] Documentation (if required)
• Code review guidelines
• Merge request performance guidelines
• Style guides
• [-] Database guides
• Separation of EE specific content

Availability and Testing

• Review and add/update tests for this feature/bug. Consider all test levels. See the Test Planning Process.
• [-] Tested in all supported browsers
• [-] Informed Infrastructure department of a default or new setting change, if applicable per definition of done