samples: zephyr: sensor: qdec: Disable on nrf54lm20pdk

Original sample in the Zephyr repository is now executed on
final board name of nrf54lm20dk/nrf54lm20a/cpuapp.

Disable execution on obsolete nrf54lm20pdk target.

Signed-off-by: Sebastian Głąb <[email protected]>

Author: nordic-segl

samples/zephyr/sensor/qdec/boards/nrf54lm20pdk_nrf54lm20a_cpuapp.overlay

@@ -10,13 +10,7 @@ common:
 
 tests:
   nrf.extended.sample.sensor.nrf_qdec_sensor:
-    platform_allow:
-      - nrf54lm20pdk/nrf54lm20a/cpuapp
-      - [email protected]/nrf54lm20a/cpuapp
-      - [email protected]/nrf54lm20a/cpuapp
-      - [email protected]/nrf54lm20a/cpuapp
-    integration_platforms:
-      - nrf54lm20pdk/nrf54lm20a/cpuapp
+    depends_on: future_target
     harness_config:
       fixture: gpio_loopback
       type: multi_line