periodic/daily/801.trim-zfs: Add a daily zfs trim script

[llfw]

As mentioned in zpoolprops(7), on some SSDs, it may not be desirable to use ZFS autotrim because a large number of trim requests can degrade disk performance; instead, the pool should be manually trimmed at regular intervals.

Add a new daily periodic script for this purpose, 801.trim-zfs. If enabled (daily_trim_zfs_enable=YES; the default is NO), it will run a 'zpool trim' operation on all online pools, or on the pools listed in 'daily_trim_zfs_pools'.

The trim is not started if the pool is degraded (which matches the behaviour of the existing 800.scrub-zfs script) or if a trim is already running on that pool. Having autotrim enabled does not inhibit the periodic trim; it's sometimes to desirable to run periodic trims even with autotrim enabled, because autotrim can elide trims for very small regions.

PR: 275965