T7965: reapply the QoS policy when the interface reconnect

[opswill]

pppoe interfaces may lose QoS config on reconnect. This PR reapplies the QoS policy when the interface comes up.

Change summary

1. QoS Fix: Adds a PPPoE hook script to /etc/ppp/ip-up.d/ to ensure QoS configuration is correctly reapplied and does not get lost when the PPPoE connection reconnects.

2. Performance Fix: As mentioned in T7965: reapply the QoS policy when the interface reconnect #4816, To avoid the significant BRAS overhead issue caused by Python interpreter startup， the QoS helper is now executed through Bash scripts.

Types of changes

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Code style update (formatting, renaming)
• Refactoring (no functional changes)
• Migration from an old Vyatta component to vyos-1x, please link to related PR inside obsoleted component
• Other (please describe):

Related Task(s)

https://vyos.dev/T7965

Related PR(s)

How to test / Smoketest result

Checklist:

• I have read the CONTRIBUTING document
• I have linked this PR to one or more Phabricator Task(s)
• I have run the components SMOKETESTS if applicable
• My commit headlines contain a valid Task id
• My change requires a change to the documentation
• I have updated the documentation accordingly

[github-actions]

👍
No issues in PR Title / Commit Title

[sarthurdev]

Why not have the hooks in the root of src/etc/ppp/ip-up.d merged into a single file?

...

if [[ "$interface" == sstpc* ]]; then
    /etc/ppp/ip-up.d/ppp-hook-scripts/96-vyos-sstpc-callback "$@"
fi

if [[ "$interface" == pppoe* ]]; then
    /etc/ppp/ip-up.d/ppp-hook-scripts/99-vyos-pppoe-callback "$@"
    /etc/ppp/ip-up.d/ppp-hook-scripts/99-vyos-pppoe-qos "$@"
fi

if [ -f "$WLB_PID_FILE" ]; then
    /etc/ppp/ip-up.d/ppp-hook-scripts/99-vyos-pppoe-wlb "$@"
fi

[opswill]

@sarthurdev The bash scripts have been merged as you suggested; only one is left in the directory.

[github-actions]

CI integration 👍 passed!

Details

CI logs

• CLI Smoketests (no interfaces) 👍 passed
• CLI Smoketests VPP ❌ failed
• CLI Smoketests (interfaces only) 👍 passed
• Config tests 👍 passed
• Config tests VPP 👍 passed
• RAID1 tests 👍 passed
• TPM tests 👍 passed

[c-po]

@opswill I just wanted to add a short comment on this - it‘s not that we do not appreciate this idea. I am currently mocking up a NETLINK daemon which we could use to hook into and drop all these helper scripts.

[opswill]

@c-po No worries at all. My patch was just intended as a direct fix for the immediate issue I encountered as a user. I completely understand that from a maintainer's perspective, a more proper solution is preferable.
Looking forward to seeing the NETLINK daemon implementation。

[dmbaturin]

@opswill Thanks for the effort and for bringing the issue to our attention! We think we'll move forward with the netlink daemon to have a general solution to this type of problems. Your future contributions are welcome.