[Catalog] fix GCP catalog missing SKUs

[cblmemo]

Fixes https://github.com/skypilot-org/skypilot-catalog/actions/runs/11760909066/job/32762128537

Tested (run the relevant ones):

• [x] Code formatting: bash format.sh
• [x] Any manual or new tests for this PR (please specify below)
  • [x] py -m sky.clouds.service_catalog.data_fetchers.fetch_gcp --single-threaded --all-regions
• [ ] All smoke tests: pytest tests/test_smoke.py
• [ ] Relevant individual smoke tests: pytest tests/test_smoke.py::test_fill_in_the_name
• [ ] Backward compatibility tests: conda deactivate; bash -i tests/backward_compatibility_tests.sh