Consider adding PID into the log message emitted by processes started by the shell

Right now, we only log the port of the mongo processes started up the mongo shell. When debugging hang analyzer stack traces or coredumps, it can often be helpful to know the PID of the process as well. We could change the logic to include the PID of the process as well e.g.

[js_test:transactions_on_secondaries_not_allowed] 2019-07-02T12:32:30.696-0400 d20021|6045|2019-07-02T12:32:30.696-0400 D2 COMMAND  [conn1] command: replSetGetStatus