samples: logging/syst: update sample for combined strings
samples: logging/syst: update sample for combined strings

Compilers often combine strings to conserve space, if one string is
a perfect substring of another one towards the end. So add another
string in the test to make sure sys-t with catalog messages is still
working correctly under this scenario.

Signed-off-by: Daniel Leung <d94e04d205b5962d7873a139ef298b03c1717f72@intel.com>

galak/zephyr,galak/zephyr,finikorg/zephyr,zephyrproject-rtos/zephyr,zephyrproject-rtos/zephyr,galak/zephyr,finikorg/zephyr,zephyrproject-rtos/zephyr,zephyrproject-rtos/zephyr,zephyrproject-rtos/zephyr,galak/zephyr,finikorg/zephyr,galak/zephyr,finikorg/zephyr,finikorg/zephyr