Optimize wgrad CUTLASS grouped gemm #18795

Job	Run time
build-macos (macos-13, shared)	22m 49s
build-windows (windows-2022, static)	12m 45s
build-windows (windows-2022, shared)	12m 26s
build-macos (macos-13, static)	13m 17s
build-bazel (x86, linux.12xlarge, clang)	9m 29s
build-bazel (x86, linux.12xlarge, gcc)	10m 1s
build-linux (arm, linux.arm64.m7g.4xlarge, shared, gcc, 14.1.0)	1h 19m 42s
build-linux (arm, linux.arm64.m7g.4xlarge, static, clang, 16.0.6)	32m 53s
build-linux (x86, linux.12xlarge, static, clang, 16.0.6)	20m 9s
build-linux (arm, linux.arm64.m7g.4xlarge, static, gcc, 14.1.0)	1h 23m 46s
build-linux (x86, linux.12xlarge, shared, gcc, 14.1.0)	26m 31s
build-linux (x86, linux.12xlarge, shared, gcc, 9.5.0)	25m 44s
build-linux (x86, linux.12xlarge, static, gcc, 14.1.0)	26m 16s
build-linux (x86, linux.12xlarge, static, gcc, 9.5.0)	25m 50s
build-linux (x86, linux.12xlarge, shared, clang, 16.0.6)	19m 56s
build-linux (arm, linux.arm64.m7g.4xlarge, shared, clang, 16.0.6)	32m 58s
	7h 34m 32s

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