Code Insights: Fix bad scrollable legend layout for small amount of legends
Created by: vovakulikov
Prior to this PR we again got a problem with overflowed content in the insight card legend block layout. The problem is even if the legend block doesn't have overflowed items we still have a scrollbar there. This problem doesn't appear in the Safari browser (that's the reason why I missed this, remained for myself - do not forget to test layout issues in different browsers)
This PR changes the scroll box component in a way to avoid this problem in Chrome, Safari, and Firefox.