Resolve "Cannot find projects within subgroups when you select a top-level group in productivity analytics"

What does this MR do?

Allows users to query projects in subgroups of a group that's been selected in Productivity Analytics.

In the screenshots below, GitLab SubProject belongs to GitLab SubOrg, which is a subgroup of GitLab Org.

Screenshots

Before	After

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

Closes #33128 (closed)