optional kernel features warning: an attribute specifier sequence in this position is a C++23 extension

https://github.com/KhronosGroup/SYCL-CTS/blob/9691bc093d4d5b8965be68bfb0716e20fda6205b/tests/optional_kernel_features/kernel_features_common.h#L336-L342

Example of build log:
```
[560/1195] Building CXX object tests/optional_kernel_features/CMakeFiles/test_optional_kernel_features_objects.dir/kernel_features_sub_group_size_exceptions.cpp.o
In file included from ../tests/optional_kernel_features/kernel_features_sub_group_size_exceptions.cpp:26:
../tests/optional_kernel_features/kernel_features_common.h:338:18: warning: an attribute specifier sequence in this position is a C++23 extension [-Wc++23-extensions]
338 | return [acc] [[sycl::device_has(AnotherFeatureAspect)]] {
| ^
../tests/optional_kernel_features/kernel_features_common.h:353:16: warning: an attribute specifier sequence in this position is a C++23 extension [-Wc++23-extensions]
353 | return [=] [[sycl::device_has(FeatureAspectT)]] {
| ^
../tests/optional_kernel_features/kernel_features_common.h:359:16: warning: an attribute specifier sequence in this position is a C++23 extension [-Wc++23-extensions]
359 | return [=] [[sycl::device_has(AnotherFeatureAspect)]] {
| ^
3 warnings generated.
```

Start with tests/optional_kernel_features/kernel_features_common.h at lines 336-342 and reproduce the warning while building the optional kernel features targets. Check the surrounding code and the affected C++ standard behavior, then verify that the build no longer emits the reported C++23-extension warnings without changing the test intent.

Written by the indexing model from the issue text.