In hs_config.c, we do validate the permission of the hidden service directory
but we do not try to create it. So, in the event that the directory doesn't
exists, we end up in the loading key code path which checks for the
permission and possibly creates the directory. On failure, don't BUG() since
there is a perfectly valid use case for that function to fail.
Fixes#27335
Signed-off-by: David Goulet <dgoulet@torproject.org>