On WDS PR's merge, we need to create a build for the release branch too
so that chromatic baselines is updated.
This PR updates the workflow to start a build on merge too.
Also, we can now remove build-storybook workflow as that is not needed
anymore since we will be building chroamtic on release also. We can use
`https://release--5f1e6db0ad879d0022744996.chromatic.com` to see the
storybook for release branch.
This PR adds the integration for chromatic which will help us catch
visual bugs in the WDS components.
The way it works is, the PR won't allowed to merge till reviewers
reviews all the changes in the components.
One thing to note is the workflow only works when there is a change in
design system files.
Fixes#21923
