zed: Cut down log spam on disk events

[tonyhutter]

System information

Type	Version/Name
Distribution Name
Distribution Version
Kernel Version
Architecture
OpenZFS Version

Describe the problem you're observing

ZED can be incredibly chatty, especially on large JBODs:

zed[534281]: zfs_iter_pool: evaluating vdevs on merced101 (by path)
zed[534281]:   zfs_iter_vdev: no match (/dev/disk/by-vdev/U4 != vdev /dev/disk/by-vdev/L0)
zed[534281]:   zfs_iter_vdev: no match (/dev/disk/by-vdev/U4 != vdev /dev/disk/by-vdev/L2)
zed[534281]:   zfs_iter_vdev: no match (/dev/disk/by-vdev/U4 != vdev /dev/disk/by-vdev/L4)
zed[534281]:   zfs_iter_vdev: no match (/dev/disk/by-vdev/U4 != vdev /dev/disk/by-vdev/L6)
zed[534281]:   zfs_iter_vdev: no match (/dev/disk/by-vdev/U4 != vdev /dev/disk/by-vdev/L8)
zed[534281]:   zfs_iter_vdev: no match (/dev/disk/by-vdev/U4 != vdev /dev/disk/by-vdev/L10)
zed[534281]:   zfs_iter_vdev: no match (/dev/disk/by-vdev/U4 != vdev /dev/disk/by-vdev/L12)
zed[534281]:   zfs_iter_vdev: no match (/dev/disk/by-vdev/U4 != vdev /dev/disk/by-vdev/L14)
zed[534281]:   zfs_iter_vdev: no match (/dev/disk/by-vdev/U4 != vdev /dev/disk/by-vdev/L16)
zed[534281]:   zfs_iter_vdev: no match (/dev/disk/by-vdev/U4 != vdev /dev/disk/by-vdev/L18)
zed[534281]:   zfs_iter_vdev: no match (/dev/disk/by-vdev/U4 != vdev /dev/disk/by-vdev/L20)
zed[534281]:   zfs_iter_vdev: no match (/dev/disk/by-vdev/U4 != vdev /dev/disk/by-vdev/L22)
zed[534281]:   zfs_iter_vdev: no match (/dev/disk/by-vdev/U4 != vdev /dev/disk/by-vdev/L24)
zed[534281]:   zfs_iter_vdev: no match (/dev/disk/by-vdev/U4 != vdev /dev/disk/by-vdev/L26)
...

Simply getting rid of the zfs_iter_vdev: no match lines will cut logs by at least half.

Describe how to reproduce the problem

Include any warning/errors/backtraces from the system logs