Remove jQuery and relpace with vue event handling

What does this MR do?

Removes the legacy jQuery from the JobGroupDropdown component and replaces it with Vue-style stopPropagation in the action component.

Screenshots

These show that in both the mini-pipeline and the big pipeline, the dropdown stays open when the action button is clicked.

Component in pipeline graph	Component in mini-graph

Does this MR meet the acceptance criteria?

Conformity

• Code review guidelines
• Merge request performance guidelines
• Style guides

Availability and Testing

• Review and add/update tests for this feature/bug. Consider all test levels. See the Test Planning Process.
• Tested in all supported browsers