Fix IPv4 alias not applied on Ysul

Summary:
Ysul has two public IPv4 addresses:

• 163.172.49.16
• 212.83.187.132 as an alias, which is the canonical public IPv4 address

However, we noticed that the alias was not actually applied on the server after applying roles/core/network.

The pillar nodes.sls was correct, but the Jinja syntax used to read the aliases was wrong.

The template used interface.get("ipv4.aliases", []), which looks for a key literally named ipv4.aliases.

It should instead read the aliases with:

interface.ipv4.get("aliases", [])

After this change, the alias is correctly generated in /etc/rc.conf.d/netif/ipv4_public and aplied on the server.

Ref T2315

Test Plan:

• salt 'ysul' state.apply roles/core/network
• Restart netif and routing
• Verify that the alias 212.83.187.132 was applied on ysul

Reviewers: dereckson, Duranzed

Reviewed By: dereckson, Duranzed

Subscribers: Duranzed, dereckson

Maniphest Tasks: T2315

Differential Revision: https://devcentral.nasqueron.org/D4095