expect file is always removed before starting a server.
So if it exists here, it means the server started successfully,
mysqltest continued executing the test, created a new expect file,
and shut down the server. All while we were waiting for the server
to start.

In other words, if the expect file exists, the server did actually start.
Even if it isn't running now.

This fixes occasional failures of innodb.log_corruption (in 10.6)