fuzz: more initialized memory for MSAN #1046

Job	Run time
build on ubuntu:24.04	1m 45s
build on ubuntu:23.10	1m 30s
build on ubuntu:22.04	1m 23s
build on ubuntu:20.04	1m 30s
build on debian:12	1m 25s
build on fedora:39	1m 54s
build on debian:11	1m 39s
build on fedora:40	1m 46s
Build dist with Linux	48s
Build Windows release (windows-latest, x86)	8m 33s
Build MacOS release (macos-14-large, amd)	1m 27s
Build Windows release (windows-latest, x64)	9m 36s
Build MacOS release (macos-latest-xlarge, arm)	53s
	34m 9s

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