Comment # 10 on bug 1178797 from Andreas Herrmann

elevator boot option is gone with block multiqueue (blk-mq) usage.
There is no point in Yast trying to set that anymore.

There is /usr/lib/udev/rules.d/60-io-scheduler.rules where basically just BFQ
is set for rotational devices.
For TW the file is part of package system-tuning-common-SUSE, for SLE15SP2 it's
part of udev 234.

I am not sure how Yast would customize I/O scheduler settings.
Writing to 60-io-scheduler.rules, create entries in a separate file?