[Core] honor allowed_cloud config in catalog lookup

[aylei]

follow up #4483 (comment)

This PR will speed up sky launch when the number of allowed clouds is small and a non-canonical GPU name is requested. As a test, with only runpod allowed in both case, this PR speed up sky launch by 4x:

# PR branch
$ /usr/bin/time sky launch --gpus L40:1
Considered resources (1 node):
---------------------------------------------------------------------------------------------
 CLOUD    INSTANCE        vCPUs   Mem(GB)   ACCELERATORS   REGION/ZONE   COST ($)   CHOSEN
---------------------------------------------------------------------------------------------
 RunPod   1x_L40_SECURE   16      48        L40:1          CA            1.14          ✔
---------------------------------------------------------------------------------------------
        0,76 real         0,89 user         2,72 sys

# master branch
$ /usr/bin/time sky launch --gpus L40:1
Considered resources (1 node):
---------------------------------------------------------------------------------------------
 CLOUD    INSTANCE        vCPUs   Mem(GB)   ACCELERATORS   REGION/ZONE   COST ($)   CHOSEN
---------------------------------------------------------------------------------------------
 RunPod   1x_L40_SECURE   16      48        L40:1          CA            1.14          ✔
---------------------------------------------------------------------------------------------
        2,94 real         1,62 user         2,61 sys

@Michaelvll PTAL, thanks!

Tested (run the relevant ones):

• Code formatting: bash format.sh
• Any manual or new tests for this PR (see test above)
• 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

[aylei]

/quicktest-core

[concretevitamin]

Nice @aylei! QQ: Some users may not explicitly set allowed_clouds and they may have very few clouds (e.g., 1) actually enabled. Namely, they may have run sky check before and we noted down 1 enabled cloud. Does this PR speedup those cases as well?

[aylei]

Nice @aylei! QQ: Some users may not explicitly set allowed_clouds and they may have very few clouds (e.g., 1) actually enabled. Namely, they may have run sky check before and we noted down 1 enabled cloud. Does this PR speedup those cases as well?

Good catch! I will update the PR to honor enabled clouds instead.