samples: rtio: disable debug log level

Avoid to build with debug log level enabled and instead register the
test log modules with debug level.

mr_canhubk3 board will fail to initialize the on-board watchdog within
the expected window triggering a reset, due to the amount of log
messages being printed. Other boards may face similar issues.

Signed-off-by: Manuel Argüelles <manuel.arguelles@nxp.com>