Remove redundant lines in the cron.d file.

Author: dajhorn

etc/zfs-auto-snapshot.cron.frequent

@@ -1,7 +1,3 @@
 PATH="/usr/bin:/bin:/usr/sbin:/sbin"
 
 */15 * * * * root zfs-auto-snapshot -q -g --label=frequent --keep=4  //
-@hourly      root zfs-auto-snapshot -q -g --label=hourly   --keep=24 //
-@daily       root zfs-auto-snapshot -q -g --label=daily    --keep=31 //
-@weekly      root zfs-auto-snapshot -q -g --label=weekly   --keep=4  //
-@monthly     root zfs-auto-snapshot -q -g --label=monthly  --keep=12 //