[SYCL][E2E] Don't override CUDA CMake vars if set (#16911)

Follow-up from #16896

Signed-off-by: Sarnie, Nick <[email protected]>

Author: sarnex

sycl/test-e2e/CMakeLists.txt

@@ -69,11 +69,13 @@ endif()
 
 set(SYCL_E2E_CLANG_CXX_FLAGS "${SYCL_E2E_CLANG_CXX_FLAGS} -Werror")
 
-find_package(CUDAToolkit)
+if(NOT DEFINED CUDA_LIBS_DIR AND NOT DEFINED CUDA_INCLUDE)
+  find_package(CUDAToolkit)
 
-if(CUDAToolkit_FOUND)
-  set(CUDA_LIBS_DIR "${CUDAToolkit_LIBRARY_DIR}")
-  set(CUDA_INCLUDE "${CUDAToolkit_INCLUDE_DIRS}")
+  if(CUDAToolkit_FOUND)
+    set(CUDA_LIBS_DIR "${CUDAToolkit_LIBRARY_DIR}")
+    set(CUDA_INCLUDE "${CUDAToolkit_INCLUDE_DIRS}")
+  endif()
 endif()
 
 if(SYCL_TEST_E2E_STANDALONE)