Revert "fix: add safety warning to pickle_memoize cache loading" (#18926)

Reverts #18925

Author: tqchen

python/tvm/contrib/pickle_memoize.py

@@ -23,7 +23,6 @@
 import os
 import pathlib
 import sys
-import warnings
 
 try:
     import cPickle as pickle
@@ -72,13 +71,6 @@ def cache(self):
         if self.path.exists():
             with self.path.open("rb") as cache_file:
                 try:
-                    warnings.warn(
-                        f"Loading cached pickle file from {self.path}. "
-                        "Pickle files can execute arbitrary code. "
-                        "Only load cache files you trust.",
-                        UserWarning,
-                        stacklevel=2,
-                    )
                     cache = pickle.load(cache_file)
                 except pickle.UnpicklingError:
                     cache = {}