[SYCL][Graph] Disable E2E tests on MTL (#19498)

Mark SYCL-Graph E2E tests as unsupported on MTL. We have built up
several bug reports on this architecture that need investigated and
fixed, see the code comment. Rather than tracking lots of individual
bugs, disable MTL until we can give the architecture a thorough
investigation and re-enable once we have fixed the bugs and are
confident in its support.

Note that unlike the other architectures in the lit file, these also
manifest on Ubuntu as well as Windows.

Author: EwanC

sycl/test-e2e/Graph/lit.local.cfg

@@ -1,3 +1,5 @@
+# MTL - CMPLRLLVM-68693, CMPLRTST-25611, CMPLRLLVM-68457
+config.unsupported_features += ['arch-intel_gpu_mtl_h', 'arch-intel_gpu_mtl_u']
 if 'windows' in config.available_features:
    # https://github.com/intel/llvm/issues/17165
    config.unsupported_features += ['arch-intel_gpu_bmg_g21', 'arch-intel_gpu_bmg_g31']