This is used only once according to HEA, but i am pretty sure this doesn't work, and probably never will.
I suggest removing it entirely.
The pref is not in sysprefs.sql
Use `git grep -i OpacGroupResults` to know where this pref is used.
Also remove PazPar2 related files ?
If the feature is tied to them it would be the consequence I think. I feel like we should bring up these kind of decisions on the mailing lists and then to a vote at the meeting.
Asked for deprecation on the list - https://lists.katipo.co.nz/pipermail/koha/2020-November/055362.html