[ncs] Increase system workqueue stack size

This PR increases the system workqueue stack size for the RCP build.
The change prevents stack exhaustion during early initialization, which
previously caused a delay in USB enumeration at boot.

Signed-off-by: Łukasz Duda <lukasz.duda@nordicsemi.no>

Author: LuDuda

config/ncs/overlay-ot-rcp-common.conf

@@ -15,3 +15,6 @@ CONFIG_LOG_BACKEND_UART=n
 CONFIG_OPENTHREAD_CSL_AUTO_SYNC=n
 CONFIG_OPENTHREAD_MIN_RECEIVE_ON_AHEAD=104
 CONFIG_OPENTHREAD_MIN_RECEIVE_ON_AFTER=0
+
+# Configure stack size of the system workqueue
+CONFIG_SYSTEM_WORKQUEUE_STACK_SIZE=1000