samples: wifi: radio_test: Fix the shields for 54 Series

Using the same arg overwrites the previous shield, they should be passed
together and in proper order.

Signed-off-by: Chaitanya Tata <[email protected]>

Author: krish2718

samples/wifi/radio_test/sample.yaml

@@ -77,8 +77,8 @@ tests:
     sysbuild: true
     build_only: true
     extra_args:
-      - radio_test_SHIELD=nrf7002eb_interposer_p1
-      - radio_test_SHIELD=nrf7002eb
+      - radio_test_SHIELD="nrf7002eb_interposer_p1;nrf7002eb"
+      - SNIPPET=nrf70-wifi
     platform_allow:
       - nrf54h20dk/nrf54h20/cpuapp
       - nrf54l15dk/nrf54l15/cpuapp