coalaJSONTest: Revert wrong variable usage

Revert the change from commit 07092f2
which mistakenly change a constant exit code value assertion when
running coala with VersionConflict error with TEST_BEARS_COUNT
constant.

Fixes coala#4551

tests/coalaJSONTest.py

@@ -113,7 +113,7 @@ def test_version_conflict_in_collecting_bears(self, import_fn, _):
             import_fn.side_effect = VersionConflict('msg1', 'msg2')
             retval, stdout, stderr = execute_coala(
                 coala.main, 'coala', '--json', '-B')
-            self.assertEqual(retval, TEST_BEARS_COUNT)
+            self.assertEqual(retval, 13)
 
     def test_text_logs(self):
         retval, stdout, stderr = execute_coala(