test(organization): align pending invitation empty-results unit case

[daryllimyt]

Summary

• rename the pending-invitations empty-state test to better reflect behavior
• use a distinct email value in the empty-results case to make intent explicit
• keep dependency override structure consistent for current_active_user

Validation

• uv run ruff check tests/unit/api/test_api_organization_invitations.py
• uv run basedpyright tests/unit/api/test_api_organization_invitations.py
• TRACECAT__SERVICE_KEY=test-service-key uv run pytest tests/unit/api/test_api_organization_invitations.py -q (fails locally in this environment because PostgreSQL on localhost:5432 was unavailable at runtime)

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Summary by cubic

Renamed the pending invitations empty-results unit test to "no_results" and used a distinct email to make the empty case explicit. Kept dependency override usage consistent across tests.

^{Written for commit 5a299bb. Summary will update on new commits.}

[cubic-dev-ai]

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