Jira integration menu item should be visible when GitLab issues are disabled

Summary

With the following update: #342466 (closed), when the Jira integration (Jira issue list) is enabled, and GitLab issues are disabled, the Jira menu item is no longer available in the left navigation.

This makes it not possible for teams that primarily use Jira to access their issues from the UI.

Reported incidents:

• https://gitlab.slack.com/archives/CETG54GQ0/p1638478876378500
• https://gitlab.slack.com/archives/C2G2VTZPA/p1639023315025900
• https://gitlab.slack.com/archives/C2G2VTZPA/p1641821192001000
• #347390 (comment 759411718)

Steps to reproduce

1. Setup a new project
2. Enable the Jira integration with the Jira issue list enabled
3. Go to the project Settings > General and under "Visibility, project features, permissions" disable "Issues"
4. Try to navigate to your Jira issue list

Example Project

What is the current bug behavior?

missing-jira-menu_1680

What is the expected correct behavior?

Ideally, the "Issues" menu item would stay visible and only display the active issue tracker (in this case Jira).

Possible fixes

When disabling GitLab issues, we should only hide the parent level "Issues" nav item, if no other issues trackers are enabled.