netifyd chores: update to 5.2.9 and add ARM64 support

[Tbaile]

Bump the netifyd DPI agent to the latest upstream release, cleanup unused plugins, deploy (for the moment the build is private) ARM64 bins.

• Remove the device-discovery processor plugin and SQLite sink plugin, they were never used, was only built for testing purposes
• Remove socket sink plugins since it's not needed anymore, moved to internal HTTP transmissions
• Disable the HTTP sink plugin by default, tools that use it drop in their configuration
• Tune netlink buffer settings to upstream's new defaults (buffer size, max buffer size, socket buffer size, conntrack idle timeout)
• Add ARM64 (aarch64) build/package support for netifyd

[Tbaile]

QA is being made manually installing the package since it's traffic based. To install it:

wget -O /tmp/netifyd-5.2.9-r1.apk https://updates.nethsecurity.nethserver.org/staging/8.8.0/packages/x86_64/nethsecurity/netifyd-5.2.9-r1.apk \
&& wget -O /tmp/ns-dpi-0.3.5-r1.apk https://updates.nethsecurity.nethserver.org/staging/8.8.0/packages/x86_64/nethsecurity/ns-dpi-0.3.5-r1.apk \
&& apk add --allow-untrusted /tmp/netifyd-5.2.9-r1.apk /tmp/ns-dpi-0.3.5-r1.apk \
&& rm /tmp/netifyd-5.2.9-r1.apk /tmp/ns-dpi-0.3.5-r1.apk

[markVnl]

For what it's worth, I cherry-picked this PR a while back to build the arm64 version.

It went well, and I've been using this image for over a week.

[Tbaile]

Ty for the feedback! Planning to release it soon, we're trying it on various systems to check it's performance.