Remove projects with disabled issues in new issue dropdown

What does this MR do and why?

This MR removes projects with disabled issues in the new issue dropdown on the group issues list page.

In the group issues page refactor behind feature flag vue_issues_list, the new issue dropdown showed all projects. The correct behaviour is that it should show only projects with issues enabled. This logic is tested in spec/features/groups/issues_spec.rb:121.

#322755 (closed)

Screenshots or screen recordings

Before (contains h5bp test again which has issues disabled`)	After (does not contain h5bp test again which has issues disabled`)

How to set up and validate locally

1. In rails console enable the feature flag

   Feature.enable(:vue_issues_list)

2. Ensure a project has issues disabled in its settings, e.g. http://127.0.0.1:3000/h5bp/h5bp-test-again/edit#js-general-project-settings
3. Visit the group issues page, e.g. http://127.0.0.1:3000/groups/flightjs/-/issues
4. Test the new issue dropdown

MR acceptance checklist

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• I have evaluated the MR acceptance checklist for this MR.