[GPU][Codegen] Support unique per-lane load option when prod(threads) < subgroupsize #47401

Job	Run time
setup / setup	9s
runtime_small	3m 13s
runtime :: ubuntu-24.04-arm	1m 45s
runtime :: windows-2022	3m 14s
runtime :: ubuntu-24.04	1m 53s
linux_x64_bazel / linux_x64_bazel	56s
linux_x64_clang / linux_x64_clang	1m 9s
runtime_tracing :: windows-2022 :: console	3m 14s
runtime_tracing :: ubuntu-24.04-arm :: tracy	1m 14s
runtime_tracing :: windows-2022 :: tracy	3m 11s
runtime :: macos-14	1m 52s
linux_x64_clang_byollvm	0s
runtime_tracing :: macos-14 :: tracy	1m 35s
runtime_tracing :: ubuntu-24.04 :: console	1m 3s
runtime_tracing :: ubuntu-24.04-arm :: console	1m 42s
runtime_tracing :: ubuntu-24.04 :: tracy	1m 10s
linux_x64_clang_debug	-1s
runtime_tracing :: macos-14 :: console	1m 20s
windows_x64_msvc	-1s
linux_x64_clang_asan / linux_x64_clang_asan	11s
linux_x64_clang_ubsan / linux_x64_clang_ubsan	2m 59s
macos_arm64_clang	-1s
linux_arm64_clang	-1s
linux_x64_gcc	-1s
macos_x64_clang	-1s
linux_x64_clang_tsan	-1s
ci_summary / summary	2s
	31m 45s

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