[Catalog] Remove hardcoded A2 pricing URL & Fix a bug in A2 machine z…

…ones (skypilot-org#1426)

* Update no 16xA100-40GB zones

* [Catalog] Remove GCP A2 price URL & Fix GCP A100 zone issues

* Add more type annotations

* Minor

* yapf

* Do not add GCP URL prefix

* Minor

* Address comments

* Address comment1

* Minor

* Add comments about the case when a100.empty is True

* Assert not duplicated