decreased discretization size for custom_symbolic test

hysop/operator/tests/test_custom_symbolic.py

@@ -34,9 +34,9 @@ class TestCustomSymbolic(object):
             cls.size_min = 4
             cls.size_max = 6
         else:
-            cls.size_min0 = 8
-            cls.size_max0 = 4096
-            cls.size_min = 8
+            cls.size_min0 = 16
+            cls.size_max0 = 16
+            cls.size_min = 16
             cls.size_max = 16
 
         cls.enable_extra_tests = enable_extra_tests