Fix the create work item group path for parent

What does this MR do and why?

This MR enabled the parent widget on the create work item to

• Select epic from any of the ancestor by passing full group path instead of the top group
• Select issue for a task in a standalone project

References

• Closes #572899 (closed)
• Closes #573034 (closed)

Screenshots or screen recordings

Scenario	Before	After
Group/project (no change)
Group/Sub group/Project
Group (no change)
Group/Sub group
root/Project (no change)

How to set up and validate locally

1. Create a nested group structure: Top Group > Subgroup A > Subgroup B > Project B.
2. Create an epic in Top Group named "Top Level Epic".
3. Create an epic in Subgroup A named "Subgroup Epic".
4. Navigate to Project B and click the button to create a New Issue.
5. In the sidebar on the right, click the "Parent" dropdown.
6. Search for "Subgroup Epic".
7. Verify the subgroup epic is shown and not just the top level epic

MR acceptance checklist

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Related to #573034 (closed)