Simplify backplaneStatus as an attempt to correct broken backplane me…

…trics (buildfarm#855)

[static analysis burndown] use String.indexOf(char) for performance

[metrics] avoid publishing target ids

Add prometheus metrics for read/write and start/stop (buildfarm#814)

Guard against exceptions in newOutput (buildfarm#780)

Ensure that the 'open' state is transitioned to cleanly. This prevents a
hang when waiting for a Write that failed to open, but set its
closedFuture member.

Ensure uncancelled getActionResult receives error (buildfarm#732)

Fixes buildfarm#731
CANCEL status exceptions can be observed from outside of the server
call. Ensure that they are propagated if the server call is not
cancelled. A race with cancellation should be mitigated by ignoring any
thrown exceptions from onError.

label CI steps as unit test (buildfarm#689)

fix issues in graceful shutdown and add separate client to test grpc …

…calls (buildfarm#647)

* create local grpc client to test grpc calls used in worker graceful shutdown

* stop matching/picking up more operations after received prepare for graceful shutdown request

* add testing

* fixing comment

* reformat

* fixing comment

fix building error caused by ShardBackplane moving (buildfarm#620)

make worker profile be able to profile all workers in a loop and moni…

…tor their status (buildfarm#592)

* get worker list from an active worker

* get worker list from redis directly

* reformat

* remove unnecessary printings

* move WorkerProfile to its own class

* add build rules for bf-workerprofile

* remove unused deps

* remove context and reformat

* make fault branch also wait for same period before next round of grpc call

* address comments