[nrf fromtree] samples: drivers: i2c: rtio_loopback: change harness to console

The harness was set to ztest, but the sample requires the console
harness to match on the "sample complete" line, its not actually
using ztest.

Signed-off-by: Bjarki Arge Andreasen <[email protected]>
(cherry picked from commit 7ee4011)

Author: bjarki-andreasen

samples/drivers/i2c/rtio_loopback/sample.yaml

@@ -5,9 +5,12 @@ tests:
     tags:
       - rtio
       - i2c_target
-    harness: ztest
+    harness: console
     harness_config:
       fixture: i2c_bus_short
+      type: one_line
+      regex:
+        - "sample complete"
     platform_allow:
       - b_u585i_iot02a
       - nrf5340dk/nrf5340/cpuapp