Remove legacy bootstrap #2400

Job	Run time
macOS [UBSAN] [lmdb \| clang]	35m 0s
macOS [ASAN] [lmdb \| clang]	29m 39s
macOS [TSAN] [lmdb \| clang]	7m 6s
macOS [UBSAN] [rocksdb \| clang]	41m 31s
macOS [ASAN] [rocksdb \| clang]	39m 14s
Linux [UBSAN] [lmdb \| clang]	38m 56s
macOS [TSAN] [rocksdb \| clang]	47m 32s
Linux [ASAN] [lmdb \| clang]	39m 25s
Linux [ASAN_INT] [lmdb \| clang] (Errors Ignored)	42m 7s
Linux [TSAN] [lmdb \| clang]	43m 30s
Linux [LEAK] [lmdb \| clang]	39m 38s
Linux [UBSAN] [rocksdb \| clang]	49m 6s
Linux [ASAN] [rocksdb \| clang]	55m 18s
Linux [ASAN_INT] [rocksdb \| clang] (Errors Ignored)	54m 12s
Linux [LEAK] [rocksdb \| clang]	54m 20s
	10h 16m 34s

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