interface: T4056: Fix unexpected delete tc qdisc

[sever-sever]

Change Summary

Traffic-policy rules are generated by old Perl code
This commit prevents to unexpected override of this code by python.
As we see in debugging it deletes tc qdisc per each interface commit:

DEBUG/IFCONFIG cmd 'tc qdisc del dev eth2 handle ffff: ingress 2> /dev/null;tc qdisc del dev eth2 handle 1: root prio 2> /dev/null;set $?=0'
DEBUG/IFCONFIG cmd 'ip link set dev eth2 up'

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://phabricator.vyos.net/T4056

Component(s) name

interface, qdisc

Proposed changes

How to test

set interfaces ethernet eth2 traffic-policy in '1G'
set traffic-policy limiter 1G default bandwidth '1gbit'
set traffic-policy limiter 1G default burst '188kb'

Expected tc values:

vyos@r11-roll# sudo tc filter show dev eth2 parent ffff:
filter protocol all pref 255 basic chain 0 
filter protocol all pref 255 basic chain 0 handle 0x1 flowid ffff:1 
	action order 1:  police 0x1 rate 1Gbit burst 192375b mtu 2Kb action drop overhead 0b 
	ref 1 bind 1

[edit]
vyos@r11-roll# 

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