De-dupe inbound SCP traffic #6307

Job	Run time
fmt	14s
build (gcc, current)	54m 30s
rust-check-git-rev-deps	18s
cargo-deny (advisories)	42s
build (gcc, current, --check-test-tx-meta)	44m 22s
cargo-deny (bans licenses sources)	44s
build (gcc, next)	57m 25s
build (gcc, next, --check-test-tx-meta)	45m 18s
build (clang, current)	48m 55s
build (clang, current, --check-test-tx-meta)	38m 33s
build (clang, next)	49m 39s
build (clang, next, --check-test-tx-meta)	39m 5s
complete	1s
	6h 19m 46s

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