Show loading state for vulnerability list when filter/sort is changed

What does this MR do?

There are 3 places where a vulnerability report is shown; for a project, for a group, and across the entire GitLab instance:

Project-level	Group-level	Instance-level

For each report, the list can be filtered and sorted. Previously, when the filter and sort were used, the list would continue showing old data until the request for new data was completed. On slower connections and for larger projects, this will make it seem nothing is happening when the request is actually still in process in the background:

This MR fixes it by showing the skeleton loader for the list whenever the filters or sort is changed:

Does this MR meet the acceptance criteria?

Conformity

• Changelog entry
• [-] Documentation (if required)
• Code review guidelines
• Merge request performance guidelines
• Style guides
• [-] Database guides
• Separation of EE specific content

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
• [-] Informed Infrastructure department of a default or new setting change, if applicable per definition of done

Related to #320885 (closed)