The old process manager's `Trace` function by default calls `log.Printf`
to output "trace" level logs. That's not ideal because by default the
trace level logs should not be outputted. In history it didn't cause
problems because there was no other call to the process manager before
the logger system's initialization.
But if there is any package using the process manager before the "Trace"
function gets assigned to the logger system's trace function, the
process manager will outputs unexpected verbose messages, this behavior
is not expected in most cases.
Now, the logger system also uses process manager to manage its goroutine
contexts, so it's the time to fix the old "trace" behavior: by default,
do not output the trace level messages. Fix#24951
7314726bab