Fix two monitoring issues after chart bump

[richard-cox]

Summary

Fixes #11592

Occurred changes and/or fixed issues

• This is a direct backport of Fix two monitoring issues after chart bump #11351

Areas or cases that should be tested

Setup

• install v2.8-head image. update rancher chart repo to point from release-2.8 to dev-v2.8 and refresh it
• enable prerelease versions from user preferences
• install monitoring 103.2.0-rc.1+up57.0.3

Validation

• nav to cluster explorer --> cluster group --> scroll down
• Alerts tab should be populated with at lease one line
• Below that grafana dashboard should be visible

Checklist

• The PR is linked to an issue and the linked issue has a Milestone, or no issue is needed
• The PR has a Milestone
• The PR template has been filled out
• The PR has been self reviewed
• The PR has a reviewer assigned
• The PR has automated tests or clear instructions for manual tests and the linked issue has appropriate QA labels, or tests are not needed
• The PR has reviewed with UX and tested in light and dark mode, or there are no UX changes