server/rz_user: reduce arbitrary 3 char limit to 1
server/rz_user: reduce arbitrary 3 char limit to 1

For first name, last name, and username.

cben/rhizi,ozFri/rhizi,cben/rhizi,yuvadm/rhizi,Rhizi/rhizi,tlevine/rhizi,shlomif/rhizi,yuvadm/rhizi,yuvadm/rhizi,ozFri/rhizi,Rhizi/rhizi,cben/rhizi,ozFri/rhizi,tlevine/rhizi,cben/rhizi,tlevine/rhizi,tlevine/rhizi,shlomif/rhizi,Rhizi/rhizi,shlomif/rhizi,Rhizi/rhizi,shlomif/rhizi,ozFri/rhizi,yuvadm/rhizi