Removes YUI usages from the plugin

[alecharp]

This is a follow up pull request of jenkinsci/jenkins#10135. This is to ensure the buttons still look appropriate if the plugin is used on a controller with no YUI available.

• Associate build to release

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• Deploy application

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• Pipeline publisher

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• Run procedure

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• Trigger release

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Testing done

I took screenshots before and after the change. No actions were triggered.

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

[scherler]

LGTM

[alecharp]

@jenkinsci/electricflow-plugin-developers do you think you could review this and potentially merge and release the plugin?