Revert 4564 and 4528

[vitorguidi]

The preprocess count for fuzz task went to zero after #4564 got deployed, reverting.

#4528 is also being reverted because it introduced the following error into the fuzz task scheduler, which caused fuzz tasks to stop being scheduled:

Traceback (most recent call last):
  File "/mnt/scratch0/clusterfuzz/src/python/bot/startup/run_cron.py", line 68, in <module>
    sys.exit(main())
             ^^^^^^
  File "/mnt/scratch0/clusterfuzz/src/python/bot/startup/run_cron.py", line 64, in main
    return 0 if task_module.main() else 1
                ^^^^^^^^^^^^^^^^^^
  File "/mnt/scratch0/clusterfuzz/src/clusterfuzz/_internal/cron/schedule_fuzz.py", line 304, in main
    return schedule_fuzz_tasks()
           ^^^^^^^^^^^^^^^^^^^^^
  File "/mnt/scratch0/clusterfuzz/src/clusterfuzz/_internal/cron/schedule_fuzz.py", line 284, in schedule_fuzz_tasks
    available_cpus = get_available_cpus(project, regions)
                     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/mnt/scratch0/clusterfuzz/src/clusterfuzz/_internal/cron/schedule_fuzz.py", line 247, in get_available_cpus
    result = pool.starmap_async(  # pylint: disable=no-member
             ^^^^^^^^^^^^^^^^^^
AttributeError: 'ProcessPoolExecutor' object has no attribute 'starmap_async'

[jonathanmetzman]

lgtm

Fascinating, I think we're not doing proper error reporitng in k8s https://pantheon.corp.google.com/errors;filter=%5B%5D?project=clusterfuzz-external&e=-13802955&mods=logs_tg_prod look