fix: silence deprecation warnings causing noisy production logs (#38128)

Co-authored-by: Claude Opus 4.6 <noreply@anthropic.com>

superset/utils/pandas_postprocessing/resample.py

@@ -54,5 +54,5 @@ def resample(
     else:
         _df = getattr(df.resample(rule), method)()
         if method in ("ffill", "bfill"):
-            _df = _df.fillna(method=method)
+            _df = getattr(_df, method)()
     return _df