worker: Fix orphaned containers on node shutdown

[victorges]

What does this pull request do? Explain your changes. (required)
This fixes the shutdown process to actually wait for the StartLivepeer function to exit,
while increasing the timeout of doing so to up to 10s. We are frequently leaving orphaned
containers behind because 2s is not enough to both stop+remove them on ai-worker logic.

This ensure we give enough time for the dockerRemoveContainer functions to run before
we exit the process.

Also, removed the RestartPolicy: always from the warm containers. This can also cause orphaned
containers in case of OS reboot, since docker will automatically restart the containers on reboot.
We already have a watchdog logic to make sure containers are healthy and restart them if not,
so the restart policy is redundant rn. Simplify it to just use up to 3 restarts on-failure for everyone.

Specific updates (required)

• Actually wait for node logic to exit before quitting
• Increase shutdown timeout
• Fix restart policy of containers

How did you test each of these updates (required)
Kill O and make sure no containers are left behind

Does this pull request close any open issues?
Fixes #3776

Checklist:

• Read the contribution guide
• make runs successfully
• All tests in ./test.sh pass
• README and other documentation updated
• Pending changelog updated

[codecov]

Codecov Report

❌ Patch coverage is 9.09091% with 10 lines in your changes missing coverage. Please review.
✅ Project coverage is 31.69676%. Comparing base (1bc682a) to head (100a641).
⚠️ Report is 1 commits behind head on master.

Files with missing lines	Patch %	Lines
cmd/livepeer/livepeer.go	0.00000%	10 Missing ⚠️

Additional details and impacted files

@@                 Coverage Diff                 @@
##              master       #3779         +/-   ##
===================================================
+ Coverage   31.68993%   31.69676%   +0.00683%     
===================================================
  Files            158         158                 
  Lines          47564       47579         +15     
===================================================
+ Hits           15073       15081          +8     
- Misses         31603       31611          +8     
+ Partials         888         887          -1     

Files with missing lines	Coverage Δ
ai/worker/docker.go	69.24399% <100.00000%> (+0.09321%)	⬆️
cmd/livepeer/livepeer.go	0.00000% <0.00000%> (ø)

... and 1 file with indirect coverage changes

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Files with missing lines	Coverage Δ
ai/worker/docker.go	69.24399% <100.00000%> (+0.09321%)	⬆️
cmd/livepeer/livepeer.go	0.00000% <0.00000%> (ø)

... and 1 file with indirect coverage changes

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