samples: subsys: usb: dfu-next: Add console harness to check expected message

- Added harness configuration to the sample.usbd.dfu
  test to avoid failing results on the bench report.
- Configured the console harness with a one_line type
  and a regex pattern to match the "USB DFU sample is initialized"
  log message.
- Ensures the test passes if the expected log message
  is found in the console output.

Signed-off-by: IBEN EL HADJ MESSAOUD Marwa <[email protected]>

Author: marwaiehm-st

samples/subsys/usb/dfu-next/sample.yaml

@@ -15,6 +15,11 @@ tests:
       - mimxrt685_evk/mimxrt685s/cm33
       - mimxrt1060_evk/mimxrt1062/qspi
     tags: usb
+    harness: console
+    harness_config:
+      type: one_line
+      regex:
+        - "USB DFU sample is initialized"
   sample.usbd.dfu-flash:
     platform_allow:
       - nrf52840dk/nrf52840