chase: when chasing paths, trigger automounts

chase: when chasing paths, trigger automounts

As it turns out open() with O_PATH does *not* trigger autofs, you get a
reference to the autofs inode, if not triggered.

But there's a way out: open_tree() (when specified without
OPEN_TREE_CLONE) is actually fully equivalent to open() with O_PATH –
with the exception of one thing: it *does* trigger automounts.

Thanks for Christian Brauner for pointing me to this and saving my day.

Fixes: #33155