[Refactor] Remove TCPiecewise Cuda Graph - #41634

XPU CI (stage-a-test-1-gpu-xpu) fails on every PR in
test/registered/xpu/test_xpu_graph.py: the tc_piecewise prefill graph
compiles the Qwen2 decoder with fullgraph=True, and since sgl-project#42301 the
forward builds msgspec.Struct layer-boundary values that Dynamo (torch
2.13) cannot construct inside a compiled region.

tc_piecewise is being removed in sgl-project#41634, so rather than reworking the
layer-boundary classes for a graph mode that is going away, skip the test
case for now and refactor the XPU graph test once sgl-project#41634 lands.

XPU CI (stage-a-test-1-gpu-xpu) fails on every PR in
test/registered/xpu/test_xpu_graph.py: the tc_piecewise prefill graph
compiles the Qwen2 decoder with fullgraph=True, and since sgl-project#42301 the
forward builds msgspec.Struct layer-boundary values that Dynamo (torch
2.13) cannot construct inside a compiled region.

tc_piecewise is being removed in sgl-project#41634, so rather than reworking the
layer-boundary classes for a graph mode that is going away, mark the
test disabled in its CI registration (run_suite.py then skips the file)
and refactor the XPU graph test once sgl-project#41634 lands.

… (#42524)

The file is also registered in the per-commit AMD suite
stage-b-test-1-gpu-large-amd, where it fails with the same
object.__new__(Contribution) error since the Qwen2 decoder was built
from stage boundaries, and its failure cancels the sibling partitions.
Both of its tests exist only to exercise tc_piecewise, which is being
removed (sgl-project#41634), so there is nothing to keep or move.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

tc_piecewise is being removed (sgl-project#41634) and M3 now defaults to breakable, so
restore these files to main.