Use deterministic replacement connection IDs

This CL removes a DoS attack vector where an attacker could grow QuicDispatcher::connection_id_map_ unboundedly. It does so by no longer using random connection IDs that are saved in connection_id_map_; instead we now generate deterministic replacement connection IDs, removing the need for a map. It should not impact the GFE because the GFE overrides QuicDispatcher::GenerateNewServerConnectionId with an already deterministic method, but is still flag protected just in case.

gfe-relnote: use deterministic replacement connection IDs, protected by new disabled flag gfe2_restart_flag_quic_deterministic_replacement_connection_ids
PiperOrigin-RevId: 264192278
Change-Id: I843bf0d846830d4b13e0bb1b470a71b2428ad7c8