Admin pubkey feature may produce duplicated keys

[sk4zuzu]

Description
Configuration like this:

    admin_pubkey: |
      {{ _admin_pubkey_loaded }}
      ssh-rsa ...
      ssh-rsa ...

is not split into separate lines, that causes idempotence issue + duplicated keys.

To Reproduce

1. Use config similar to the one above.
2. Run ansible-playbook.

Expected behavior
No duplicates, correctly working idempotence.

Details

• Ansible version: N/A
• Linux OS distro in your cluster: N/A
• Version: 1.1.0

Additional context
N/A

Progress Status

• Code committed
• Testing - QA
• Documentation (Release notes - resolved issues, compatibility, known issues)