gfe-relnote: Remove DUPLICATE_PUSH frame. Protected by gfe2_reloadable_flag_quic_enable_version_draft_25_v3 and gfe2_reloadable_flag_quic_enable_version_draft_27. DUPLICATE_PUSH frame has been removed from HTTP/3 specs at https://github.com/quicwg/base-drafts/pull/3309. PiperOrigin-RevId: 300117789 Change-Id: I39aef6d20829fca9185de9aa1272e4cd707782c7