Configuration of grpc_health_probe command

[tstirrat15]

The operator has liveness and readiness probes configured. However, the timeout on that probe is a bit misleading, because that's the timeout of the invocation of the command, rather than a timeout that's used by the command itself.

The command is defined here, and the timeout can be configured by flags but there is not currently a flag on the operator for that.

It'd be nice to make the timeouts agree with each other for clarity's sake, and it might be nice to make the probe configurable (though understanding that 1s is a long time for a gRPC connection to be established).

Discord thread for reference