[JENKINS-69860] - onclick usage un-inlined for CSP compliance.

[Artmorse]

The issue
You can find all the issue details here.

My updates:
I've created a credentialOK.js file to externalized the javascript and I've updated the credentialOK.jelly file.

• 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

[Artmorse]

Closed because we don't need the Close button anymore (see the PR#48).

[Artmorse]

Someone can add the hacktoberfest and hacktoberfest-accepted labels to this PR because it seems that this repository is not participating in Hacktoberfest ? 😊