Update DbfsArtifactRepository logic that checks whether DBFS FUSE is …

…available to not write to stdout (mlflow#1478)

mlflow/utils/databricks_utils.py

@@ -1,3 +1,4 @@
+import os
 import logging
 import subprocess
 
@@ -52,10 +53,12 @@ def is_in_databricks_notebook():
 
 
 def is_dbfs_fuse_available():
-    try:
-        return subprocess.call(["mountpoint", "/dbfs"]) == 0
-    except Exception:  # pylint: disable=broad-except
-        return False
+    with open(os.devnull, 'w') as devnull_stderr, open(os.devnull, 'w') as devnull_stdout:
+        try:
+            return subprocess.call(
+                ["mountpoint", "/dbfs"], stderr=devnull_stderr, stdout=devnull_stdout) == 0
+        except Exception:  # pylint: disable=broad-except
+            return False
 
 
 def get_notebook_id():