bt: update bt bqr event mask property value

* set BtBqrEventMaskOverride value to 262238 in bt_vendor_overlay.conf
  to disable firmware BTRT logging.

Bug: 237906721
Test: Manually
Change-Id: Ic509d750dcbbd8089df73c454d29f40bfe433716

bluetooth/bt_vendor_overlay.conf

@@ -5,3 +5,6 @@ UartPort = /dev/ttySAC18
 
 # Sar backOff high resolution support
 SarBackOffHighResolution = true
+
+# Update BQR Event Mask property value
+BqrEventMaskValueUpdate = 262238