[Grid] Fix system.datetime filter never matching non-midnight values

DateTimeFilter::apply passed roundToDay=false to applySystemDatetimeFilter,
which makes GDI's DateFilter collapse gte and lte to the same instant for
"on" queries — and similarly turn from/to into exact instant boundaries.
The filter UI exposes only a date picker (no time), so an exact-instant
match here never succeeds for stored datetime values whose time component
is non-zero. DateFilter (system.date) already passes roundToDay=true;
DateTimeFilter should too.

Author: markus-moser

src/DataIndex/Filter/DateTimeFilter.php

@@ -32,8 +32,11 @@ public function apply(mixed $parameters, QueryInterface $query): QueryInterface
             return $query;
         }
 
+        // The filter UI is date-only, so "on" / range queries are always whole-day matches.
+        // Without rounding, GDI's DateFilter collapses gte/lte to the same instant and never
+        // matches stored datetimes with a non-zero time component.
         foreach ($parameters->getColumnFilterByType(ColumnType::SYSTEM_DATETIME->value) as $column) {
-            $query = $this->applySystemDatetimeFilter($column, $query, false);
+            $query = $this->applySystemDatetimeFilter($column, $query, true);
         }
 
         return $query;