In quic, coalesce packet of higher encryption level with initial or handshake retransmission. protected by gfe2_reloadable_flag_quic_coalesced_packet_of_higher_space. The goal of this change is to mitigate inflated RTT sample. PiperOrigin-RevId: 321556627 Change-Id: I7fc8675bb0f05a48b6e81ed4aa9c04b42fb0690a