[predicates] keep making `yes` predicate importable from cubicweb (closes #2790319) The `yes` predicate was moved out in CubicWeb 3.15 but it should have remained importable from the cubicweb.predicates module, for bw compat reasons and also because logilab.common.registry is an implementation detail.

sql('DROP FUNCTION IF EXISTS _fsopen(bytea)')
sql('DROP FUNCTION IF EXISTS fspath(bigint, text, text)')