This regressed in https://github.com/element-hq/synapse/pull/19121. I
moved things in https://github.com/element-hq/synapse/pull/19121 because
I thought that it made sense to redirect anything printed to
`stdout`/`stderr` to the logs as early as possible. But we actually want
to log any immediately apparent problems during initialization to
`stderr` in the terminal so that they are obvious and visible to the
operator.
Now, I've moved `redirect_stdio_to_logs()` back to where it was
previously along with some proper comment context for why we have it
there.
db00925ae7