fuzz: Add cross-version ChannelMonitor roundtrip coverage #23361

Job	Run time
check_docs	7m 8s
check_release	3m 10s
linting	2m 33s
fuzz_sanity	19m 56s
fuzz	1h 41m 4s
rustfmt	16s
ext-test	5m 8s
tor-connect	6m 57s
benchmark	18m 1s
build-workspace / build (self-hosted, 1.75.0)	14m 3s
build-cfg-flags / build (self-hosted, 1.75.0)	11m 40s
build-sync / build (self-hosted, 1.75.0)	20m 55s
build-features / build (self-hosted, 1.75.0)	33m 28s
build-nostd / build (self-hosted, 1.75.0)	21m 20s
build-bindings / build (self-hosted, 1.75.0)	28m 51s
coverage	0s
notify-failure	0s
	4h 54m 30s

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