[JENKINS-70464] Improve EmbeddableBadgeConfigsActionTest test coverage

[abhishekmaity]

In response to #114,

Testing done

• Increased the test coverage of existing EmbeddableBadgeConfigsActionTest.java
• Improved test coverage shown below

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

[MarkEWaite]

Thanks!