(#22384) Log 404 and 406 responses at info

When the specific exception classes for HTTP control flow were
introduced, they ended up changing the logging from info to notice.
Notice is a much more severe level, which doesn't warrant having simple
file not found errors showing up at it. This changes the level back to
info.
Merge pull request #1895 from zaphod42/issue/stable/22384-excessive-logging

(#22384) Log 404 and 406 responses at info