Use quiche string libraries in third_party/quic/core (part 2) Looks like some more occurrences of the Quic libraries cropped up between cl/285401547 and now. gfe-relnote: n/a, no functional change PiperOrigin-RevId: 285408322 Change-Id: I4ee4a869d5027c2568a299e56fec4a54eec1dfca