tmpfiles: fix borked assert

It seems that fd_set_perms() is always called after checking that
fd >= 0 (also when called as action() in glob_item_recursively()),
so it seems that the assertion really came from fd==0.

Fixes #20140.

Also three other similar cases are updated.

(cherry picked from commit b4b0f87c)
(cherry picked from commit 1dcecfc5)
(cherry picked from commit 5f2d3e45)