outgoingfw: Use local timezone for time rules.

See bug #10305:
  https://bugzilla.ipfire.org/show_bug.cgi?id=10305
Revert "outgoingfw: Use local timezone for time rules."

This reverts commit 21ef1f15f6807277b756f5be4dd6f320c665a74c.

This has no effect as the kernel usually runs in UTC. If --kerneltz
is missing, UTC will be used as well.