Add accumulative bugs by priority in stage and group views

We already have the accumulative bugs at the top-level dashboard.

• https://quality-dashboard.gitlap.com/groups/gitlab-org/bugs_by_priority

Per @joshlambert's suggestion we would like to have this chart in the stage/group views as well for bugs in those areas.

This should be a relatively simple change since we are just replicating the chart at a different scope.

cc @gl-quality/eng-prod