IMPALA-4676: remove vestigial references to getBlockStorageLocations() API
The BlockStorageLocation import is unused.
Remove validation of config keys that only affect the
BlockStorageLocation API. See
HDFS-10868 and HDFS-8895. We do not
need to validate these keys any more since we don't use that API.
These config keys are removed in Hadoop 3 so this patch is
required to build against it.
Reviewed-by: Tim Armstrong <email@example.com>
Tested-by: Impala Public Jenkins