remove DFS availability test

tests/test_data_manager.py

@@ -45,5 +45,6 @@ class TestCsstMsDataManager(unittest.TestCase):
         self.assertTrue(isinstance(self.dm_sls.l1_detector(1, post="flt.fits"), str))
         self.assertTrue(isinstance(self.dm_sls.l1_file(name="some_file.ext", comment="a demo file"), str))
 
-    def test_dfs_is_available(self):
-        self.assertTrue(self.dm_mbi.dfs_is_available())
+    # DFS is not always available
+    # def test_dfs_is_available(self):
+    #     self.assertTrue(self.dm_mbi.dfs_is_available())