[Core] Relax cluster name restrictions and process cluster names #11271

Job	Run time
python-test (3.8, tests/unit_tests)	4m 41s
python-test (3.8, tests/test_api.py)	2m 35s
python-test (3.8, tests/test_cli.py)	2m 35s
python-test (3.8, tests/test_config.py)	2m 30s
python-test (3.8, tests/test_global_user_state.py)	2m 46s
python-test (3.8, tests/test_jobs.py)	2m 48s
python-test (3.8, tests/test_list_accelerators.py)	2m 39s
python-test (3.8, tests/test_optimizer_dryruns.py)	4m 59s
python-test (3.8, tests/test_optimizer_random_dag.py)	3m 40s
python-test (3.8, tests/test_storage.py)	2m 28s
python-test (3.8, tests/test_wheels.py)	2m 34s
python-test (3.8, tests/test_spot.py)	2m 34s
python-test (3.8, tests/test_yaml_parser.py)	2m 27s
	39m 16s

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