[NFC] XFAIL bfloat16_integeral_convesions in spirv-backend run mode

Author: jsji

sycl/test-e2e/DeviceLib/imf/bfloat16_integeral_convesions.cpp

@@ -1,5 +1,7 @@
 // RUN: %{build} -o %t1.out
 // RUN: %{run} %t1.out
+// XFAIL: spirv-backend && run-mode
+// XFAIL-TRACKER: https://github.com/intel/llvm/issues/20853 
 
 #include "imf_utils.hpp"
 #include <sycl/detail/core.hpp>