Do not constrain visit_system in data query

Instead of constraining visit_system to 0 in the data query,
only define the one-to-one (visitSystem=0) visits in the repo.
This preserves the bahavior and makes it also work with
non-on-sky exposures that cannot take visit constraint in the
data query.

python/activator/middleware_interface.py

@@ -438,7 +438,7 @@ def _init_visit_definer(self):
 
         ``self._init_local_butler`` must have already been run.
         """
-        define_visits_config = lsst.obs.base.DefineVisitsConfig()
+        define_visits_config = lsst.obs.base.DefineVisitsConfig(groupExposures="one-to-one")
         self.define_visits = lsst.obs.base.DefineVisitsTask(config=define_visits_config, butler=self.butler)
 
     def _define_dimensions(self):
@@ -1353,7 +1353,6 @@ def run_pipeline(self, exposure_ids: set[int]) -> None:
         where = (
             f"instrument='{self.visit.instrument}' and detector={self.visit.detector}"
             f" and exposure in ({','.join(str(x) for x in exposure_ids)})"
-            " and visit_system = 0"
         )
         preload_run = self._get_preload_run(self._day_obs)
         init_pre_runs = [self._get_init_output_run(f, self._day_obs) for f in self._get_pre_pipeline_files()]