chore(node): normalize config.sh to return empty string #23943

Job	Run time
Bazel Test All	6m 40s
Bazel Build All Config Check	0s
Bazel Build Fuzzers	1m 43s
Bazel Build Fuzzers AFL	1m 57s
Bazel Test macOS Intel	0s
Build IC	11m 50s
Python CI Tests	1m 50s
Cargo Build Release Linux	9s
Cargo Clippy Linux	9s
Build Determinism (//publish/binaries:upload, release, build-ic/release, false)	12s
Build Determinism (//publish/canisters:upload, canisters, build-ic/canisters, false)	16s
Build Determinism (//ic-os/guestos/envs/prod:upload_disk-img, guest-os/update-img, build-ic/icos/...	22s
Build Determinism (//ic-os/hostos/envs/prod:upload_update-img, host-os/update-img, build-ic/icos/...	12s
Build Determinism (//ic-os/setupos/envs/prod:upload_disk-img, setup-os/disk-img, build-ic/icos/se...	14s
	25m 34s

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