[SE-3333] Update default branch to juniper.3

This pull request is about updating the default branch to juniper.3.

Jira ticket

• SE-3333

Dependencies

This PR depends on: open-craft/ansible-secrets#209

Testing instructions

1. Deploy the changes and verify that a working Juniper (juniper.3) instance is spawned.

Author notes and concerns

n/a

Reviewers

• @nizarmah