Rewrite QuicTypesTest.QuicIetfTransportErrorCodeString. This test did not make any sense. It enforced that internal QuicErrorCodes beyond QUIC_PACKET_TOO_LARGE did not map to defined IETF on-the-wire error codes. This is contradictory to our efforts to send an IETF-compliant error code for each QuicErrorCodes code. gfe-relnote: n/a, test-only change. PiperOrigin-RevId: 300394002 Change-Id: I054df8252e8ebb9238ff4fffab1b08632e5bba24