De-dupe inbound SCP traffic #6306

Job	Run time
rust-check-git-rev-deps	15s
build (gcc, current)	54m 15s
cargo-deny (advisories)	42s
build (gcc, current, --check-test-tx-meta)	42m 6s
fmt	14s
cargo-deny (bans licenses sources)	48s
build (gcc, next)	59m 30s
build (gcc, next, --check-test-tx-meta)	45m 58s
build (clang, current)	47m 20s
build (clang, current, --check-test-tx-meta)	37m 51s
build (clang, next)	50m 10s
build (clang, next, --check-test-tx-meta)	39m 3s
complete	1s
	6h 18m 13s

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