Expand error message in ValidateComputeStageWorkgroupSize #4725

Job	Run time
CMake-windows-latest-Debug-msvc	13m 5s
Go Build and Test	44s
CMake-windows-latest-Release-msvc	17m 7s
CMake-ubuntu-latest-Debug-gcc	20m 35s
CMake-ubuntu-latest-Release-gcc	20m 54s
CMake-macos-latest-Debug-clang	23m 40s
CMake-macos-latest-Release-clang	24m 17s
CMake-macos-13-Debug-clang	52m 33s
CMake-macos-13-Release-clang	49m 59s
	3h 42m 54s

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