Fix ledger_priority.sequential_blocks testcase #2513

Job	Run time
macOS [UBSAN] [lmdb \| clang]	30m 28s
macOS [ASAN] [lmdb \| clang]	29m 19s
macOS [TSAN] [lmdb \| clang]	29m 7s
Linux [UBSAN] [lmdb \| clang]	39m 42s
macOS [UBSAN] [rocksdb \| clang]	36m 6s
Linux [ASAN] [lmdb \| clang]	37m 18s
macOS [ASAN] [rocksdb \| clang]	36m 10s
Linux [ASAN_INT] [lmdb \| clang] (Errors Ignored)	38m 27s
macOS [TSAN] [rocksdb \| clang]	49m 50s
Linux [TSAN] [lmdb \| clang]	41m 1s
Linux [LEAK] [lmdb \| clang]	40m 6s
Linux [UBSAN] [rocksdb \| clang]	46m 55s
Linux [ASAN] [rocksdb \| clang]	53m 26s
Linux [ASAN_INT] [rocksdb \| clang] (Errors Ignored)	52m 35s
Linux [LEAK] [rocksdb \| clang]	54m 30s
	10h 15m 0s

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