feat(iroh): improve Router shutdown #11526

Job	Run time
Android Build Only (aarch64-linux-android)	1m 10s
Android Build Only (armv7-linux-androideabi)	1m 7s
Cross Build Only (x86_64-unknown-freebsd)	46s
Cross Test (i686-unknown-linux-gnu)	2m 12s
Build wasm32	40s
cargo deny	28s
Checking docs	1m 40s
Checking fmt	24s
check_semver	4m 34s
clippy_check	2m 15s
codespell	5s
Minimal Supported Rust Version	1m 42s
CI Test Suite / Tests (ubuntu-latest, stable, all)	2m 4s
CI Test Suite / Tests (ubuntu-latest, stable, none)	1m 54s
CI Test Suite / Tests (ubuntu-latest, stable, default)	1m 49s
CI Test Suite / Tests (macOS-arm-latest, stable, all)	2m 17s
CI Test Suite / Tests (macOS-arm-latest, stable, none)	1m 59s
CI Test Suite / Tests (macOS-arm-latest, stable, default)	2m 2s
CI Test Suite / Tests (windows-latest, stable, all, x86_64-pc-windows-msvc)	2m 16s
CI Test Suite / Tests (windows-latest, stable, none, x86_64-pc-windows-msvc)	2m 23s
CI Test Suite / Tests (windows-latest, stable, default, x86_64-pc-windows-msvc)	2m 28s
netsim-integration-tests / Netsim	6m 4s
	42m 19s

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