CMP: add testcase for central keygen #1197

Job	Run time
compiler (gcc-7, ubuntu-20.04)	4m 23s
compiler (gcc-8, ubuntu-20.04)	4m 19s
compiler (gcc-9, ubuntu-20.04)	4m 32s
compiler (gcc-10, ubuntu-20.04)	4m 14s
compiler (gcc-11, ubuntu-22.04)	4m 26s
compiler (gcc-12, ubuntu-22.04)	4m 50s
compiler (gcc-13, ubuntu-22.04, ubuntu-toolchain-r/test)	8m 32s
compiler (clang-6.0, ubuntu-20.04)	39s
compiler (clang-7, ubuntu-20.04)	37s
compiler (clang-8, ubuntu-20.04)	41s
compiler (clang-9, ubuntu-20.04)	44s
compiler (clang-10, ubuntu-20.04)	35s
compiler (clang-11, ubuntu-20.04)	31s
compiler (clang-12, ubuntu-20.04)	36s
compiler (clang-13, ubuntu-22.04)	40s
compiler (clang-14, ubuntu-22.04)	39s
compiler (clang-15, ubuntu-22.04, jammy)	42s
compiler (clang-16, ubuntu-22.04, jammy)	43s
compiler (clang-17, ubuntu-22.04, jammy)	45s
	43m 8s

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