a couple of tests cast CL_DEVICE_IMAGE_MAX_BUFFER_SIZE value to int

There are a handful of tests, which case the returned value of `CL_DEVICE_IMAGE_MAX_BUFFER_SIZE` to an `int`, e.g. https://github.com/KhronosGroup/OpenCL-CTS/blob/be8b56d94972b4d159e7471aebf5e9ab302d4d81/test_conformance/images/clCopyImage/test_copy_1D_buffer.cpp#L185

This will become a problem on GPUs with more than ~32GiB of VRAM (an implementation can effectively return 1/16 of `CL_DEVICE_MAX_MEM_ALLOC_SIZE` for `CL_DEVICE_IMAGE_MAX_BUFFER_SIZE`)

Start with test_conformance/images/clCopyImage/test_copy_1D_buffer.cpp at the referenced cast, then search the image tests for other casts of CL_DEVICE_IMAGE_MAX_BUFFER_SIZE. Update each affected test so larger values are preserved, and verify the tests no longer truncate values above the 32 GiB range.

Written by the indexing model from the issue text.