Cleanup resolver specs and verify user object presence

What does this MR do and why?

This MR adds a guard to prevent auth checks on a nil user object. This is a spin-off from a sentry error reported on a similar code path Fix NoMethodError for OrganizationClusterAgents... (!200013 - merged)

This MR also deletes old GraphQL specs targeting a deprecated endpoint, and renames the existing specs to conform to the resolver name.

References

Fix NoMethodError for OrganizationClusterAgents... (!200013 - merged)

Screenshots or screen recordings

Before	After

How to set up and validate locally

This is an additional guard; it should be sufficient as a verification for scripts/remote_development/run-smoke-test-suite.sh to pass when run.

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