Prepare for React 19 prior to Grafana 13 release

[VikaCep]

With Grafana 13 planned to move to React 19, we have to make sure to test compatibility and address any issues ahead of the stable release. Recommended actions:

Check plugin compatibility
Use the grafana/react-detect tool to identify which incompatible React APIs your plugin is using. We also recommend reviewing this document on the upcoming React 19 upgrade, which provides a deeper explanation of the planned changes and their impact on plugin development.|

Update your workflows to v6.0.0
We've just released v6.0.0 of plugin-ci-workflows, which extends the E2E version matrix to include a preview Grafana image built with React 19. Updating your workflows allows you to see how your plugin behaves in a React 19 environment using your existing test suite.

Managing E2E failures and PR merges
Depending on your repository rulesets, the E2E matrix may be required to merge PRs. If the React 19 preview fails and you still need to merge, you can exclude the React19 image from the matrix by setting the following input to false:
run-playwright-with-skip-grafana-react-19-preview-image: false
If you have questions, feel free to reach out in #proj-react-19. :thank-you: