Include failure context in splice events #23074

Job	Run time
ext-test	6m 54s
benchmark	17m 1s
fuzz	1h 3m 52s
check_docs	5m 13s
linting	2m 32s
rustfmt	16s
build-nostd / build (self-hosted, 1.75.0)	17m 2s
tor-connect	5m 52s
build-features / build (self-hosted, 1.75.0)	37m 6s
build-bindings / build (self-hosted, 1.75.0)	21m 41s
build-cfg-flags / build (self-hosted, 1.75.0)	16m 28s
check_release	2m 53s
build-workspace / build (self-hosted, 1.75.0)	19m 4s
fuzz_sanity	16m 20s
build-sync / build (self-hosted, 1.75.0)	23m 14s
coverage	26m 14s
notify-failure	0s
	4h 41m 42s

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