Remove legacy bootstrap #2396

Job	Run time
Linux [UBSAN] [lmdb \| clang]	41m 1s
Linux [ASAN] [lmdb \| clang]	42m 41s
Linux [ASAN_INT] [lmdb \| clang] (Errors Ignored)	41m 38s
Linux [TSAN] [lmdb \| clang]	43m 27s
Linux [LEAK] [lmdb \| clang]	41m 39s
Linux [UBSAN] [rocksdb \| clang]	52m 8s
macOS [UBSAN] [lmdb \| clang]	35m 22s
Linux [ASAN] [rocksdb \| clang]	55m 56s
macOS [ASAN] [lmdb \| clang]	33m 4s
Linux [ASAN_INT] [rocksdb \| clang] (Errors Ignored)	57m 30s
macOS [TSAN] [lmdb \| clang]	33m 53s
Linux [LEAK] [rocksdb \| clang]	56m 13s
macOS [UBSAN] [rocksdb \| clang]	46m 33s
macOS [ASAN] [rocksdb \| clang]	47m 23s
macOS [TSAN] [rocksdb \| clang]	51m 59s
	11h 20m 27s

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