oeqa/qemurunner: Use logger.debug, not logger.info

oeqa/qemurunner: Use logger.debug, not logger.info

Bitbake logs info messages to the console. These messages are really
there as debugging information. At the debug level, they will be shown
in failure logs and in the task logs but not on the console which
is what we want in this case.

Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>