feat: Switch base to mcr-r2021b-update-7-java-8.9-slim

What is your Merge about?

Updating to a slimmer base image, matlab-runtime:mcr-r2021b-update-7-java-8.9-slim

For more information please visit Iron Bank Documentation

Note: Please be sure you create an issue related to this merge request and the issue is labeled StatusReview, this will initiate a CHT member review of your merge request.