[mk/Debian] Fix gbp options

   - Disable multimaint-merge opt
   - Use git-like order of commits
   - Add git sha prefix to each commit entry

   Closes-PROD: https://mirantis.jira.com/browse/PROD-19766

Change-Id: I8a9decf8094ce889d976828c99b59e742439341a
1 file changed