Improve plugin discoverability in UC

### Your checklist for this issue

🚨 Please review the [guidelines for contributing](../blob/master/docs/CONTRIBUTING.md) to this repository.

- [ ] Link to any upstream changes that might be required (for example Jenkins Core pull request)

### Feature Request

On an instance without the plugin installed, typing Casc/ JCasc won't display the plugin (but will display another that has Casc in its description). One need to type "configuration" to see the plugin.
This can be misleading for end users as the plugin is known and called JCasc/Casc in a lot of places. Proposal would be to add JCASC and CASC as additional labels in the UC for this plugin.

Read docs/CONTRIBUTING.md first, then locate the plugin metadata used by the Jenkins Update Center. Verify how the plugin is currently identified for search and add the JCASC and CASC labels so both terms find it; confirm the resulting metadata or relevant checks pass.

Written by the indexing model from the issue text.