[CodeStyle][F821] fix undefined variables due to missing imports, misspelled variable names (#47899)

* `hann` -> `_hann`

* `false` -> `False`

* a missing passed argument `reduce_all`

* some missing imports

* `device_type` -> `heter_device_type`

* `PKVClient` -> `KVClient`

* fix some typos and missing imports