test(app_trace): add SystemView UART tracing tests for all targets

docs/en/migration-guides/release-6.x/6.0/system.rst

@@ -81,6 +81,26 @@ Update to:
         return res;
     }
 
+The UART destination configuration has been simplified:
+
+- Removed: Individual UART selection via ``CONFIG_APPTRACE_DEST_UARTx=y``
+- Added: Single UART port selection via ``CONFIG_APPTRACE_DEST_UART_NUM``
+
+To migrate, update your sdkconfig:
+
+Old configuration:
+.. code-block:: none
+
+    CONFIG_APPTRACE_DEST_UART0=y
+    # or
+    CONFIG_APPTRACE_DEST_UART1=y
+
+New configuration:
+.. code-block:: none
+
+    CONFIG_APPTRACE_DEST_UART=y
+    CONFIG_APPTRACE_DEST_UART_NUM=0  # or 1, 2 depending on target
+
 FreeRTOS
 --------