[DevOps Adoption] Add totals line to "trend over time" graph

Overview

A trend over time graph was added to DevOps Adoption in #337561 (closed). The graph shows columns for Dev Sec and Ops. An aggregation of all features would provide visibility into the overall trends in an organization's devops journey.

Summary

• Add a blue line to the graph that shows the total adoption (percentage of the total number of features for all of Dev, Sec, Ops).
• Match the blue color to the blue for "Overall adoption" in the section higher on the page.
• Add the blue line to the legend with a label "Total adoption"

Disclaimer

This page may contain information related to upcoming products, features and functionality. It is important to note that the information presented is for informational purposes only, so please do not rely on the information for purchasing or planning purposes. Just like with all projects, the items mentioned on the page are subject to change or delay, and the development, release, and timing of any products, features or functionality remain at the sole discretion of GitLab Inc.

This page may contain information related to upcoming products, features and functionality. It is important to note that the information presented is for informational purposes only, so please do not rely on the information for purchasing or planning purposes. Just like with all projects, the items mentioned on the page are subject to change or delay, and the development, release, and timing of any products, features, or functionality remain at the sole discretion of GitLab Inc.