filt_timerexpire_l(): re-insert restarted timer into head instead of tail

of the resumed timers list, so that kqtimer_proc_continue() does not
iterated into the same timer again.

PR: 293141
Reviewed by: markj
Sponsored by: The FreeBSD Foundation
MFC after: 3 days
Differential revision: https://reviews.freebsd.org/D55264