Update annotations configs to add arrows

What does this MR do?

Currently, annotations are passed as props to area/line charts and are added as data points in a second series (decorative series). Interacting with annotations when there are many data points is very difficult.

Now that a second tooltip for annotations has been added gitlab-ui!1288 (merged), annotations will be added as markLines and markPoints instead of data points. markPoints are located at the bottom of the chart and does not interfere with the data points interaction. This way hovering over annotations becomes easier.

Notes

1. The annotations feature is behind metrics_dashboard_annotations feature flag.
2. GitLab UI version update is no longer required as master has newest version. 1. The GitLab UI versions of annotations tooltip is 11.6.0 and current version is 11.2.1. It is going to be a drastic change to do such an upgrade. While this is being reviewed, I will figure out if it is a safe upgrade. From the changelog it looks like there aren't any breaking changes so this should be good. https://gitlab.com/gitlab-org/gitlab-ui/-/blob/master/CHANGELOG.md

Demo

https://gitlab-org.gitlab.io/gitlab-ui/?path=/story/charts-area-chart--with-annotations

Screenshots

Before	After

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

Security

If this MR contains changes to processing or storing of credentials or tokens, authorization and authentication methods and other items described in the security review guidelines:

• Label as security and @ mention @gitlab-com/gl-security/appsec
• The MR includes necessary changes to maintain consistency between UI, API, email, or other methods
• Security reports checked/validated by a reviewer from the AppSec team

Mentions: #211418 (closed)