Adapt filenotify-tests.el for Emba

Adapt filenotify-tests.el for Emba

* test/infra/gitlab-ci.yml (.filenotify-gio-template): Enable also
for scheduled jobs.

* test/lisp/filenotify-tests.el (file-notify--test-cleanup):
Fix docstring.
(file-notify--deftest-remote): Use `file-notify--test-cleanup'.
(file-notify-test03-events, file-notify-test05-file-validity)
(file-notify-test06-dir-validity)
(file-notify-test07-many-events)
(file-notify-test09-watched-file-in-watched-dir): Adapt tests.
(file-notify-test03-events-remote)
(file-notify-test04-autorevert-remote)
(file-notify-test07-many-events-remote)
(file-notify-test09-watched-file-in-watched-dir-remote): Do not
tag as :unstable.

(cherry picked from commit 771370dea50834d585664bfd3ca7320d24a94611)