router: reduce unnecessary `String` allocations #3130

Job	Run time
check-style	14s
clippy-lint	26s
build-and-test (ubuntu-22.04, all)	2m 4s
build-and-test (ubuntu-22.04, default)	2m 6s
build-and-test (windows-2022, all)	1m 49s
build-and-test (windows-2022, default)	1m 49s
build-and-test (macos-14, all)	1m 49s
build-and-test (macos-14, default)	1m 51s
	12m 8s

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