Fix suspected bug in AutoGreylist::Reset() #2173

Job	Run time
Lint	47s
macOS 13 native [GOAL install] [GUI] [no depends]	9m 47s
ARM [GOAL install] [bullseye]	2m 41s
Win32	3m 18s
Win64	4m 25s
i386 Linux [GOAL install] [focal]	2m 10s
x86_64 Linux [GOAL install] [GUI] [focal] [no depends]	15m 43s
x86_64 Linux [GOAL install] [GUI] [noble] [no depends]	1h 14m 54s
x86_64 Linux [ASan] [LSan] [UBSan] [integer] [jammy] [no depends]	5m 14s
macOS 10.14 [GOAL deploy] [GUI] [no tests] [noble]	3m 14s
arm64 macOS 10.14 [GOAL deploy] [GUI] [no tests] [noble]	3m 14s
	2h 5m 27s

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