[QPG] Lower OpenThread task priority to mitigate race conditions in Matter code (project-chip#40152)

Co-authored-by: Adam Bodurka <[email protected]>

Author: kliffwong

src/platform/qpg/CHIPDevicePlatformConfig.h

@@ -54,6 +54,10 @@
 #define CHIP_DEVICE_CONFIG_THREAD_TASK_STACK_SIZE (4 * 1024)
 #endif // CHIP_DEVICE_CONFIG_THREAD_TASK_STACK_SIZE
 
+#ifndef CHIP_DEVICE_CONFIG_THREAD_TASK_PRIORITY
+#define CHIP_DEVICE_CONFIG_THREAD_TASK_PRIORITY 3
+#endif
+
 #define CHIP_DEVICE_CONFIG_MAX_EVENT_QUEUE_SIZE 25
 
 #define CHIP_DEVICE_CONFIG_ENABLE_WIFI_TELEMETRY 0