Remove legacy bootstrap #2399

Job	Run time
Linux [UBSAN] [lmdb \| clang]	42m 38s
Linux [ASAN] [lmdb \| clang]	41m 10s
Linux [ASAN_INT] [lmdb \| clang] (Errors Ignored)	40m 11s
Linux [TSAN] [lmdb \| clang]	40m 1s
Linux [LEAK] [lmdb \| clang]	38m 48s
Linux [UBSAN] [rocksdb \| clang]	49m 0s
Linux [ASAN] [rocksdb \| clang]	55m 6s
Linux [ASAN_INT] [rocksdb \| clang] (Errors Ignored)	56m 47s
Linux [LEAK] [rocksdb \| clang]	53m 57s
macOS [UBSAN] [lmdb \| clang]	35m 41s
macOS [ASAN] [lmdb \| clang]	31m 53s
macOS [TSAN] [lmdb \| clang]	32m 48s
macOS [UBSAN] [rocksdb \| clang]	39m 19s
macOS [ASAN] [rocksdb \| clang]	38m 43s
macOS [TSAN] [rocksdb \| clang]	51m 27s
	10h 47m 29s

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