hibari >> gh33 (bad sequence) and gh34 (scavenger enhancements):

Revert the following change at #7749814bf. It broke local logs by
adding some extra bytes between metadata hunks.

- REVERTED: A bug fix in write_hunk_bytes of gmt_hlog_local:
  * fix a potential bug in handle_call/3 for 'write_hunk_bytes' with
    'metadata', which causes to return a wrong offset.