Allow Gitaly N+1 calls for RootController#index

What does this MR do?

Allow developers to load GitLab root page locally without errors. Since we know this issue for a while now, no point letting the exception be triggered constantly.

See also https://gitlab.com/gitlab-org/gitlab-ce/blob/master/doc/development/gitaly.md#toomanyinvocationserror-errors

What are the relevant issue numbers?

https://gitlab.com/gitlab-org/gitlab-ce/issues/37434

https://gitlab.com/gitlab-org/gitlab-ce/issues/40260

Does this MR meet the acceptance criteria?

• [-] Changelog entry added, if necessary
• [-] Documentation created/updated via this MR
• [-] Documentation reviewed by technical writer or follow-up review issue created
• [-] Tests added for this feature/bug
• [-] Tested in all supported browsers
• Conforms to the code review guidelines
• Conforms to the merge request performance guidelines
• Conforms to the style guides
• [-] Conforms to the database guides
• [-] Link to e2e tests MR added if this MR has Requires e2e tests label. See the Test Planning Process.
• Security reports checked/validated by reviewer