Disallow database operations on network IO threads #2410

Job	Run time
macOS [UBSAN] [lmdb \| clang]	36m 38s
Linux [UBSAN] [lmdb \| clang]	38m 59s
macOS [ASAN] [lmdb \| clang]	27m 29s
Linux [ASAN] [lmdb \| clang]	36m 43s
macOS [TSAN] [lmdb \| clang]	29m 46s
Linux [ASAN_INT] [lmdb \| clang] (Errors Ignored)	37m 44s
macOS [UBSAN] [rocksdb \| clang]	40m 22s
macOS [ASAN] [rocksdb \| clang]	36m 13s
Linux [TSAN] [lmdb \| clang]	37m 26s
macOS [TSAN] [rocksdb \| clang]	45m 29s
Linux [LEAK] [lmdb \| clang]	37m 8s
Linux [UBSAN] [rocksdb \| clang]	47m 55s
Linux [ASAN] [rocksdb \| clang]	47m 55s
Linux [ASAN_INT] [rocksdb \| clang] (Errors Ignored)	50m 20s
Linux [LEAK] [rocksdb \| clang]	50m 0s
	10h 0m 7s

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