[SYCL][NFC] Fix check-work-group-attributes-match.cpp for AMDGPU

[wenju-he]

b3ca5fb introduced amdgpu-flat-work-group-size attributes with per-kernel values, causing each kernel to get a distinct attribute group (#0, #2, #4) on amdgcn targets. Relax the attribute group checks from the hardcoded #0 to #{{[0-9]+}}.

Fixes CodeGenSYCL/check-work-group-attributes-match.cpp CMPLRLLVM-76303

[bader]

@wenju-he, SYCL doesn't support AMDGPU anymore. Do we need to maintain both b3ca5fb and c53885f changes in this repository?
It makes sense either to submit both to llvm-project or revert both and remove the test to simplify the maintanance.

@intel/dpcpp-cfe-reviewers, @tahonermann, what do you think?

[tahonermann]

Since intel/llvm/dpclang is now being productized and beginning to be included in Linux distributions, I think caution is warranted with regard to discarding support for other vendor hardware. We might begin to see contributions outside of Intel as the SYCL ecosystem grows; which could be a considerable benefit to Intel. For that reason, I think it is worth putting minimal effort towards keeping what currently works working as a gesture of good will to the SYCL community. I don't think doing so conflicts with Intel's goals to prioritize support for its own products.

[wenju-he]

will try to upstream #22452
Other fixes are lit tests that fail in pulldown. Removing amdgpu RUN lines should be done separately if needed, so it is the task from pulldown coordinator.

[wenju-he]

so it is the task from pulldown coordinator.

sorry, I mean it is not the task from pulldown coordinator.