Use jenkins-button over yui-button in 'New domain' and 'Update domain' screens

[janfaracik]

Small PR to use the jenkins-button class over yui-button in the 'New domain' and 'Update domain' screens.

Before

After

Testing done

• Button behaves as expected
• Disables when there isn't a name, enables when there is.

Submitter checklist

• Make sure you are opening from a topic/feature/bugfix branch (right side) and not your main branch!
• Ensure that the pull request title represents the desired changelog entry
• Please describe what you did
• Link to relevant issues in GitHub or Jira
• Link to relevant pull requests, esp. upstream and downstream changes
• Ensure you have provided tests - that demonstrates feature works or fixes the issue

[mawinter69]

This is also covered by #533