T775: Config-sync bracketize IPv6 secondary address

[sever-sever]

Change Summary

bracketize IPv6 remote address to avoid Failed to parse: https://2001:db8::2/configure-section

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/T775

Component(s) name

config-sync

Proposed changes

How to test

VyOS configuration:

set service config-sync mode 'load'
set service config-sync secondary address '2001:db8::2'
set service config-sync secondary key 'foo'
set service config-sync section 'nat'
set service config-sync section 'firewall'

set nat source rule 100 description '222'
set nat source rule 100 outbound-interface 'eth0'
set nat source rule 100 source address '192.0.2.0/24'
set nat source rule 100 translation address 'masquerade'

Commit before the fix:

vyos@r14# commit
INFO:vyos_config_sync:Config synchronization: Mode=load, Secondary=2001:db8::2
An error occurred: Failed to parse: https://2001:db8::2/configure-section
ERROR:vyos_config_sync:An error occurred: Failed to parse: https://2001:db8::2/configure-section
An error occurred: Failed to parse: https://2001:db8::2/configure-section
ERROR:vyos_config_sync:An error occurred: Failed to parse: https://2001:db8::2/configure-section
[edit]
vyos@r14# 

Commit after the fix:

vyos@r14# commit
[ nat ]

INFO:vyos_config_sync:Config synchronization: Mode=load, Secondary=[2001:db8::2]
[edit]
vyos@r14# 

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