Fix log_file for Savanna-api

Backport for 4.1.1
Closes-bug: 1301905

Change-Id: I49b193a59c4b907e15e2a3071ba0d799586aba5d
Signed-off-by: Bogdan Dobrelya <bdobrelia@mirantis.com>
Merge "Fix log_file for Savanna-api" into stable/4.1