avoid re-opening hdf file multiple times in read_hdf

closes dask#10204

this is a performance optimization that also bypasses the
pandas bug pandas-dev/pandas#52781

Author: graingert

dask/dataframe/io/hdf.py

@@ -436,10 +436,10 @@ def read_hdf(
     # Build metadata
     with pd.HDFStore(paths[0], mode=mode) as hdf:
         meta_key = _expand_key(key, hdf)[0]
-    try:
-        meta = pd.read_hdf(paths[0], meta_key, mode=mode, stop=0)
-    except IndexError:  # if file is empty, don't set stop
-        meta = pd.read_hdf(paths[0], meta_key, mode=mode)
+        try:
+            meta = pd.read_hdf(hdf, meta_key, stop=0)
+        except IndexError:  # if file is empty, don't set stop
+            meta = pd.read_hdf(hdf, meta_key)
     if columns is not None:
         meta = meta[columns]