[SYCL][E2E] Minor clean up of test directives (#20246)

Remove `-std=c++20` from a couple of tests. It is not needed, and if it
is then we should use `%cxx_std_optionc++20` instead, for Windows

Author: cperkinsintel

sycl/test-e2e/ESIMD/regression/bit_shift_vector_compilation_test_pvc.cpp

@@ -6,7 +6,7 @@
 //
 //===---------------------------------------===//
 
-// RUN: %{build} -fsycl-device-code-split=per_kernel -std=c++20 -o %t.out
+// RUN: %{build} -fsycl-device-code-split=per_kernel -o %t.out
 // RUN: %{run} %t.out
 // REQUIRES: arch-intel_gpu_pvc
 

sycl/test-e2e/ESIMD/rotate_pvc.cpp

@@ -6,9 +6,9 @@
 //
 //===----------------------------------------------------------------------===//
 
-// RUN: %{build} -fsycl-device-code-split=per_kernel -std=c++20 -o %t.out
+// RUN: %{build} -fsycl-device-code-split=per_kernel -o %t.out
 // RUN: %{run} %t.out
-// RUN: %{build} -fsycl-device-code-split=per_kernel -std=c++20 -o %t1.out -DEXP
+// RUN: %{build} -fsycl-device-code-split=per_kernel -o %t1.out -DEXP
 // RUN: %{run} %t1.out
 // REQUIRES: arch-intel_gpu_pvc