Fix remaining localhost fallback in playground Request URL display #7

Job	Run time
test (windows-latest)	6h 0m 6s
lint	3m 43s
build (ubuntu-latest, x86_64-unknown-linux-musl, jemalloc)	4m 51s
test (ubuntu-latest)	6h 0m 14s
build (macos-latest, aarch64-apple-darwin, default)	15m 36s
build (ubuntu-22.04-arm, aarch64-unknown-linux-musl, default)	4m 38s
build (windows-latest, x86_64-pc-windows-msvc, default)	17m 23s
	12h 46m 31s

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