Removes Yahoo UI usages from support-core plugin

[sandeepbarnwal]

Changes

• Replaced yui button references with jenkins-button

Note: button location got changed (renders on left side now) after using jenkins-button css and it seemed more in line with the other buttons. Hence, I didn't put effort to keep it in original location and would change if required after the reviews.

Testing done

Before

After

Submitter checklist

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• 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

[batmat]

@sandeepbarnwal the difference between before and after screenshot wrt. bundle namings sounds surprising (and very different). Did you test it with the same instance?

[sandeepbarnwal]

@sandeepbarnwal the difference between before and after screenshot wrt. bundle namings sounds surprising (and very different). Did you test it with the same instance?

thanks for the observation. It was from different insrance (from modern setup in local machine). Now, I've update the before screenshot that matches with the after one.