multiseries

What does this MR do?

Only show dots & values for lines that have a value where the mouse is

metrics

For test data: git revert --no-commit 853ea7445eeaff6581a48f5111466275b87b1003

What are the relevant issue numbers?

Closes https://gitlab.com/gitlab-org/gitlab-ce/issues/50947

Does this MR meet the acceptance criteria?

• Changelog entry added, if necessary
• Documentation created/updated
• Tests added for this feature/bug
• Conforms to the code review guidelines
• Conforms to the merge request performance guidelines
• Conforms to the style guides
• Conforms to the database guides