Stopped conditional discovery of gis_tests apps

Refs #23879.

tests/gis_tests/models.py

@@ -0,0 +1,18 @@
+from django.core.exceptions import ImproperlyConfigured
+
+try:
+    from django.contrib.gis.db import models
+except ImproperlyConfigured:
+    from django.db import models
+
+    class DummyField(models.Field):
+        def __init__(self, dim=None, srid=None, geography=None, *args, **kwargs):
+            super(DummyField, self).__init__(*args, **kwargs)
+
+    models.GeoManager = models.Manager
+    models.GeometryField = DummyField
+    models.LineStringField = DummyField
+    models.MultiPointField = DummyField
+    models.MultiPolygonField = DummyField
+    models.PointField = DummyField
+    models.PolygonField = DummyField