fix(iroh-gossip): do not drop existing connection on incoming one #8378

Job	Run time
clippy_check	2m 23s
Checking fmt	7s
check_semver	4m 17s
Checking docs	1m 6s
Build wasm32	34s
Minimal Supported Rust Version	1m 24s
Cross compile (i686-unknown-linux-gnu)	2m 30s
Cross compile (armv7-linux-androideabi)	1m 1s
cargo deny	49s
Cross compile (aarch64-linux-android)	59s
Run network simulations/benchmarks	7m 27s
CI Test Suite / Tests (windows-latest, stable, all, x86_64-pc-windows-msvc)	3m 49s
CI Test Suite / Tests (ubuntu-latest, stable, all)	2m 32s
CI Test Suite / Tests (windows-latest, stable, none, x86_64-pc-windows-msvc)	3m 50s
CI Test Suite / Tests (ubuntu-latest, stable, none)	2m 52s
CI Test Suite / Tests (windows-latest, stable, default, x86_64-pc-windows-msvc)	3m 45s
CI Test Suite / Tests (ubuntu-latest, stable, default)	2m 14s
CI Test Suite / Tests (macOS-arm-latest, stable, all)	3m 9s
CI Test Suite / Tests (macOS-arm-latest, stable, none)	2m 52s
CI Test Suite / Tests (macOS-arm-latest, stable, default)	2m 56s
	50m 36s

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