Log PID of run_bot process (#4382)

This should allow us to figure out why certain processes are OOMing.

Related: b/376094981

src/python/bot/startup/run_bot.py

@@ -192,6 +192,8 @@ def main():
 
   fuzzers_init.run()
 
+  logs.info(f'PID is {os.getpid()}')
+
   if environment.is_trusted_host(ensure_connected=False):
     from clusterfuzz._internal.bot.untrusted_runner import host
     host.init()