T5535: firewall: migrate command <set system ip disable-directed-broadcast> to firewall global-optinos (backport #3309)

[mergify]

Change Summary

Migrate command to firewall global-optinos

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/T5535

Related PR(s)

Component(s) name

firewall

Proposed changes

How to test

vyos@vyos# run show config comm | grep firewall
[edit]
vyos@vyos# sudo cat /proc/sys/net/ipv4/conf/all/bc_forwarding
1
[edit]
vyos@vyos# set firewall global-options directed-broadcast 
Possible completions:
   enable               Enable IPv4 directed broadcast forwarding on all interfaces (default)
   disable              Disable IPv4 directed broadcast forwarding on all interfaces
      
[edit]
vyos@vyos# set firewall global-options directed-broadcast disable 
[edit]
vyos@vyos# commit
[edit]
vyos@vyos# sudo cat /proc/sys/net/ipv4/conf/all/bc_forwarding
0
[edit]
vyos@vyos# del firewall 
[edit]
vyos@vyos# commit
[edit]
vyos@vyos# sudo cat /proc/sys/net/ipv4/conf/all/bc_forwarding
1
[edit]
vyos@vyos# 

Smoketest result

test_firewall.py -> OK
test_system_ip.py -> OK

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

---

This is an automatic backport of pull request #3309 done by [Mergify](https://mergify.com).