Adapt tests and manual for w32notify

Adapt tests and manual for w32notify

* doc/lispref/os.texi (File Notifications): w32notify does not
send `attribute-changed' events.

* test/automated/file-notify-tests.el (file-notify--test-with-events):
Simplify parameters.  Adapt all callees.
(file-notify-test02-events): w32notify does not send
`attribute-changed' events.
(file-notify-test04-file-validity, file-notify-test05-dir-validity):
Do not skip in case of w32notify.  Simply ignore this part of the test.