Add ubuntu image for GCP

[Michaelvll]

skypilot-org/skypilot#1641

We need to increase the catalog version for the users to get the latest catalogs

Note: everything except for the gcp/images.csv is directly copied from the v5

[concretevitamin]

Question: is it correct that "implementing auto GCP catalog fetching & keep it at V5" is an alternative to bumping everything to V6? If so, any preference?

cc @WoosukKwon

[Michaelvll]

Question: is it correct that "implementing auto GCP catalog fetching & keep it at V5" is an alternative to bumping everything to V6? If so, any preference?

cc @WoosukKwon

We can apply the auto update argument in our code, which will update the catalog for the user every 7 hours, but for this one, if the user update to skypilot-org/skypilot#1641, if there catalog is not updated immediately, it is possible that the problem mentioned in skypilot-org/skypilot#1641 (review) still occurs. That said, I would prefer update to v6

[concretevitamin]

Can we do something like

https://github.com/skypilot-org/skypilot/blob/master/sky/clouds/service_catalog/common.py#L90-L91

to check if a GCP catalog's .md5 exists, so that after upgrading the user's catalog would be immediately updated?

(Rationale is (orthogonal to this PR) I have been finding our versioning confusing, as in when to update and what each version means. A treatment that makes more intuitive sense is to only bump versions for "schema changes". Content changes, like adding more images or updating prices, should not require version bumping. Perhaps they should require timestamp bumping instead.)