[SYCL][CUDA][HIP] Remove CUDA and HIP PI unit tests (#12459)

These tests are not currently running and are covered in other test
suites:

* `test_primary_context.cpp`
  * Deprecated feature, covered in `test-e2e/Basic/context.cpp`
* `test_commands.cpp`
  * Covered by UR CTS
* `test_sampler_properties.cpp`
* Covered by UR CTS:
https://github.com/oneapi-src/unified-runtime/tree/main/test/conformance/sampler
* `PlatformTest.cpp`
* Covered by UR CTS:
https://github.com/oneapi-src/unified-runtime/blob/main/test/conformance/platform/urPlatformGetInfo.cpp
* `test_device.cpp`
* Covered by UR CTS:
https://github.com/oneapi-src/unified-runtime/blob/main/test/conformance/device/urDeviceGetInfo.cpp
* `EnqueueMemTest.cpp`
* Covered by UR CTS:
https://github.com/oneapi-src/unified-runtime/blob/main/test/conformance/enqueue/urEnqueueMemBufferFill.cpp
* `test_mem_obj.cpp`
  * Moved to UR CTS
* `test_contexts.cpp`
*
https://github.com/oneapi-src/unified-runtime/blob/main/test/adapters/cuda/context_tests.cpp
* `test_kernels.cpp`
*
https://github.com/oneapi-src/unified-runtime/blob/main/test/adapters/cuda/kernel_tests.cpp
* `test_base_objects.cpp`
  * Basic tests mostly covered in UR
* `test_interop_get_native.cpp`
  * Mostly covered in UR tests and E2E tests

After this both the CUDA and HIP directories could be removed. There are
two PI tests remaining, one with regards to xpti handling of PI call
arguments, and one regarding OpenCL interop ownership.

sycl/unittests/pi/CMakeLists.txt

@@ -1,9 +1,7 @@
 set(CMAKE_CXX_EXTENSIONS OFF)
 
 add_sycl_unittest(PiTests OBJECT
- EnqueueMemTest.cpp
  PiMock.cpp
- PlatformTest.cpp
  PiUtility.cpp
  pi_arguments_handler.cpp
  piInteropRetain.cpp
@@ -13,11 +11,3 @@ add_dependencies(PiTests sycl)
 target_include_directories(PiTests PRIVATE SYSTEM ${sycl_inc_dir})
 target_include_directories(PiTests PRIVATE ${sycl_src_dir}/../tools/xpti_helpers)
 
-if("cuda" IN_LIST SYCL_ENABLE_PLUGINS)
- add_subdirectory(cuda)
-endif()
-
-if("hip" IN_LIST SYCL_ENABLE_PLUGINS)
- add_subdirectory(hip)
-endif()
-