samples/ipc/ipc_service: fix sample.yaml caused -D <empty> issue

Utilizing yaml "folding" with ">" for extra_args split
into multiple lines without spurious newline added.

Signed-off-by: Andrzej Puzdrowski <andrzej.puzdrowski@nordicsemi.no>

Author: nvlsianpu

samples/ipc/ipc_service/sample.yaml

@@ -21,68 +21,61 @@ tests:
       - nrf5340dk/nrf5340/cpuapp
     integration_platforms:
       - nrf5340dk/nrf5340/cpuapp
-
   sample.ipc.ipc_service.nrf5340dk_rpmsg_cpuapp_sending:
     platform_allow:
       - nrf5340dk/nrf5340/cpuapp
     integration_platforms:
       - nrf5340dk/nrf5340/cpuapp
     extra_configs:
       - CONFIG_APP_IPC_SERVICE_SEND_INTERVAL=1
-    extra_args:
+    extra_args: >
       remote_CONFIG_APP_IPC_SERVICE_SEND_INTERVAL=200000000
-
   sample.ipc.ipc_service.nrf5340dk_rpmsg_cpunet_sending:
     platform_allow:
       - nrf5340dk/nrf5340/cpuapp
     integration_platforms:
       - nrf5340dk/nrf5340/cpuapp
     extra_configs:
       - CONFIG_APP_IPC_SERVICE_SEND_INTERVAL=200000000
-    extra_args:
+    extra_args: >
       remote_CONFIG_APP_IPC_SERVICE_SEND_INTERVAL=1
-
   sample.ipc.ipc_service.nrf5340dk_icmsg_default:
     platform_allow:
       - nrf5340dk/nrf5340/cpuapp
     integration_platforms:
       - nrf5340dk/nrf5340/cpuapp
-    extra_args:
+    extra_args: >
       FILE_SUFFIX=icmsg
-
   sample.ipc.ipc_service.nrf5340dk_icmsg_cpuapp_sending:
     platform_allow:
       - nrf5340dk/nrf5340/cpuapp
     integration_platforms:
       - nrf5340dk/nrf5340/cpuapp
     extra_configs:
       - CONFIG_APP_IPC_SERVICE_SEND_INTERVAL=35
-    extra_args:
+    extra_args: >
       FILE_SUFFIX=icmsg
       remote_CONFIG_APP_IPC_SERVICE_SEND_INTERVAL=200000000
-
   sample.ipc.ipc_service.nrf5340dk_icmsg_cpunet_sending:
     platform_allow:
       - nrf5340dk/nrf5340/cpuapp
     integration_platforms:
       - nrf5340dk/nrf5340/cpuapp
     extra_configs:
       - CONFIG_APP_IPC_SERVICE_SEND_INTERVAL=200000000
-    extra_args:
+    extra_args: >
       FILE_SUFFIX=icmsg
       remote_CONFIG_APP_IPC_SERVICE_SEND_INTERVAL=1
-
   sample.ipc.ipc_service.nrf54h20dk_cpuapp_cpurad_icmsg:
     platform_allow:
       - nrf54h20dk/nrf54h20/cpuapp
     integration_platforms:
       - nrf54h20dk/nrf54h20/cpuapp
-
   sample.ipc.ipc_service.nrf54h20dk_cpuapp_cpuppr_icmsg:
     platform_allow:
       - nrf54h20dk/nrf54h20/cpuapp
     integration_platforms:
       - nrf54h20dk/nrf54h20/cpuapp
-    extra_args:
+    extra_args: >
       FILE_SUFFIX=cpuppr
       ipc_service_SNIPPET=nordic-ppr