Simplify message visitor #1014

Job	Run time
Linux [UBSAN] [lmdb \| clang]	39m 28s
Linux [ASAN] [lmdb \| clang]	23m 35s
macOS [UBSAN] [lmdb \| clang]	33m 21s
macOS [ASAN] [lmdb \| clang]	29m 0s
Linux [ASAN_INT] [lmdb \| clang] (Errors Ignored)	13m 18s
macOS [TSAN] [lmdb \| clang] (Errors Ignored)	32m 53s
macOS [UBSAN] [rocksdb \| clang]	41m 1s
Linux [TSAN] [lmdb \| clang] (Errors Ignored)	13m 43s
Linux [LEAK] [lmdb \| clang] (Errors Ignored)	23m 52s
macOS [ASAN] [rocksdb \| clang]	47m 5s
Linux [UBSAN] [rocksdb \| clang]	43m 45s
macOS [TSAN] [rocksdb \| clang] (Errors Ignored)	52m 54s
Linux [ASAN] [rocksdb \| clang]	26m 17s
Linux [ASAN_INT] [rocksdb \| clang] (Errors Ignored)	51m 35s
Linux [TSAN] [rocksdb \| clang] (Errors Ignored)	12m 48s
Linux [LEAK] [rocksdb \| clang] (Errors Ignored)	23m 32s
	8h 28m 7s

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