[OCI] Set default image to ubuntu LTS 22.04 #18845

Job	Run time
python-test (3.8, tests/unit_tests)	3m 23s
python-test (3.8, tests/test_api.py)	37s
python-test (3.8, tests/test_cli.py)	54s
python-test (3.8, tests/test_config.py)	37s
python-test (3.8, tests/test_global_user_state.py)	28s
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)	2m 3s
python-test (3.8, tests/test_optimizer_random_dag.py)	48s
python-test (3.8, tests/test_storage.py)	28s
python-test (3.8, tests/test_wheels.py)	32s
python-test (3.8, tests/test_jobs_and_serve.py)	26s
python-test (3.8, tests/test_yaml_parser.py)	27s
	11m 58s

Provide feedback