fix: labels on cloudeventsources CRD should be the same as other CRDs

[JoelDimbernat]

Use the same labels for all CRDs.

Checklist

• [x] I have verified that my change is according to the deprecations & breaking changes policy
• [x] Commits are signed with Developer Certificate of Origin
• [x] README is updated with new configuration values N/A
• [x] A PR is opened to update KEDA core (repo) N/A

[zroubalik]

Thanks