In Python 2 Kafka message value gets implicitly converted to unicode in
delivery_report function. In case the message value already contains
unicode characters the convertion fails with UnicodeDecodeError.
This case can be reproduced when trying to run:
u'goose: {}'.format('gęś')
This commit fixes the debug message and avoids implicit type convertion.
Change-Id: Ia9463cd4e9f92cdf18b092abd2cf676aa4966679
Story: 2006503
Task: 36481