[Jobs] Managed jobs database use WAL mode

[Michaelvll]

WAL is more robust for more parallel access, as we have done for #3863 #3923

Tested (run the relevant ones):

• Code formatting: bash format.sh
• Any manual or new tests for this PR (please specify below)
  • Launch 1000 jobs with a 64 core CPU controller.

    import subprocess
    from multiprocessing.pool import ThreadPool
    
    def run_task(task):
        print(f'Running task {task}')
        subprocess.run(
            f'sky jobs launch -n job-{task} -dy --fast --cloud aws -t t3.medium --use-spot "echo hi {task}; sleep 3600"',
            shell=True
        )
    
    with ThreadPool(8) as pool:
        pool.map(run_task, range(1000))
    
    

• 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

[concretevitamin]

Move this closer to use site?

(Technically, googlestyle defines the ordering of members, funcs, etc.; but we haven't been following that ordering consistently.)

[concretevitamin]

Are these formatting changes from the recent pylint hook?

[Michaelvll]

Yes, we recently updated pylint to use sky/ instead of sky which includes those files without __init__.py in the parent folder. #4184