Use start/stop patter in `block_processor` #852

Job	Run time
macOS [UBSAN] [lmdb \| clang]	31m 21s
Linux [UBSAN] [lmdb \| clang]	39m 38s
macOS [ASAN] [lmdb \| clang]	28m 22s
Linux [ASAN] [lmdb \| clang]	40m 3s
macOS [TSAN] [lmdb \| clang] (Errors Ignored)	28m 37s
macOS [UBSAN] [rocksdb \| clang]	39m 32s
Linux [ASAN_INT] [lmdb \| clang] (Errors Ignored)	39m 53s
macOS [ASAN] [rocksdb \| clang]	37m 52s
Linux [TSAN] [lmdb \| clang] (Errors Ignored)	36m 53s
macOS [TSAN] [rocksdb \| clang] (Errors Ignored)	1h 11m 25s
Linux [LEAK] [lmdb \| clang] (Errors Ignored)	36m 45s
Linux [UBSAN] [rocksdb \| clang]	43m 35s
Linux [ASAN] [rocksdb \| clang]	49m 27s
Linux [ASAN_INT] [rocksdb \| clang] (Errors Ignored)	50m 8s
Linux [TSAN] [rocksdb \| clang] (Errors Ignored)	1h 35m 31s
Linux [LEAK] [rocksdb \| clang] (Errors Ignored)	45m 55s
	11h 54m 57s

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