Did we reach to the consensus for the name to central? I was thinking a head actor. (And in the same way, head dashboard). I think it'll be great to keep using the consistent terminology.

@rkooo567 Not necessarily. We can change it to "head" or "primary". I just wanted to open up this PR to make a) make sure I know what changes are required and b) to get this done before it slips my mind.

Can one of the admins verify this patch?

Test PASSed.
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https://amplab.cs.berkeley.edu/jenkins//job/Ray-PRB/27867/
Test PASSed.

Test FAILed.
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https://amplab.cs.berkeley.edu/jenkins//job/Ray-PRB/27922/
Test FAILed.

Closing to reopen with new name & no merge conflicts