[querier] fix eid relations handling in SET queries (closes #2797052)
_extract_eid_consts() implementation must consider arithmetic operators
when trying to associate rql variables to specific eids.
[system]
db-driver = postgres
db-host = localhost
db-port = 5433
adapter = native
db-name = cw_fti_test
db-encoding = UTF-8
db-user = syt
db-password = syt
[admin]
login = admin
password = gingkow