[Core] make per-cloud catalog lookup parallel (#4483) #19019

Job	Run time
python-test (3.8, tests/unit_tests)	4m 0s
python-test (3.8, tests/test_api.py)	34s
python-test (3.8, tests/test_cli.py)	54s
python-test (3.8, tests/test_config.py)	34s
python-test (3.8, tests/test_global_user_state.py)	27s
python-test (3.8, tests/test_jobs.py)	33s
python-test (3.8, tests/test_list_accelerators.py)	42s
python-test (3.8, tests/test_optimizer_dryruns.py)	1m 49s
python-test (3.8, tests/test_optimizer_random_dag.py)	1m 43s
python-test (3.8, tests/test_storage.py)	23s
python-test (3.8, tests/test_wheels.py)	27s
python-test (3.8, tests/test_jobs_and_serve.py)	29s
python-test (3.8, tests/test_yaml_parser.py)	23s
	12m 58s

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