luci-mod-network: IPv6 traceroute timeouts in extreme condition

[emi-YFcz5XDj]

Steps to reproduce:

1. Open Network > Diagnostics
2. Traceroute 4321::1234
3. Wait

Actual behavior:

Error: XHR request timed out

Expected behavior:

Traceroute outputs appear in the text box

Additional Information:

NAME="OpenWrt"
VERSION="SNAPSHOT"
ID="openwrt"
ID_LIKE="lede openwrt"
PRETTY_NAME="OpenWrt SNAPSHOT"
VERSION_ID="snapshot"
HOME_URL="https://openwrt.org/"
BUG_URL="https://bugs.openwrt.org/"
SUPPORT_URL="https://forum.openwrt.org/"
BUILD_ID="r26992-bbcd5111cb"
OPENWRT_BOARD="mediatek/filogic"
OPENWRT_ARCH="aarch64_cortex-a53"
OPENWRT_TAINTS=""
OPENWRT_DEVICE_MANUFACTURER="OpenWrt"
OPENWRT_DEVICE_MANUFACTURER_URL="https://openwrt.org/"
OPENWRT_DEVICE_PRODUCT="Generic"
OPENWRT_DEVICE_REVISION="v0"
OPENWRT_RELEASE="OpenWrt SNAPSHOT r26992-bbcd5111cb"