module/zfs: remove zfs_zevent_console and zfs_zevent_cols

zfs_zevent_console committed multiple printk()s per line without
properly continuing them ‒ a single event could easily be fragmented
across over thirty lines, making it useless for direct application

zfs_zevent_cols exists purely to wrap the output from zfs_zevent_console

The niche this was supposed to fill can be better served by something
akin to the all-syslog ZEDLET

Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Signed-off-by: Ahelenia Ziemiańska <nabijaczleweli@nabijaczleweli.xyz>
Closes #7082
Closes #11996