Remove legacy bootstrap #2402

Job	Run time
macOS [UBSAN] [lmdb \| clang]	36m 51s
Linux [UBSAN] [lmdb \| clang]	41m 46s
macOS [ASAN] [lmdb \| clang]	28m 13s
Linux [ASAN] [lmdb \| clang]	38m 34s
macOS [TSAN] [lmdb \| clang]	33m 1s
Linux [ASAN_INT] [lmdb \| clang] (Errors Ignored)	39m 56s
macOS [UBSAN] [rocksdb \| clang]	41m 53s
Linux [TSAN] [lmdb \| clang]	39m 49s
macOS [ASAN] [rocksdb \| clang]	38m 48s
Linux [LEAK] [lmdb \| clang]	41m 55s
macOS [TSAN] [rocksdb \| clang]	50m 35s
Linux [UBSAN] [rocksdb \| clang]	48m 29s
Linux [ASAN] [rocksdb \| clang]	52m 42s
Linux [ASAN_INT] [rocksdb \| clang] (Errors Ignored)	54m 15s
Linux [LEAK] [rocksdb \| clang]	53m 4s
	10h 39m 51s

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