What problem does this PR solve?:

The metadata yaml file for cloudnative-pg app has dependencies and category fields set to an empty array. The dependency field should be removed and category should be set as "general" if it is not categorized. 
Setting dependencies field as empty array [], causes UI to render empty name (see screenshot in the ticket), a bug in kommander-ui which is being tracked here .
For now, as we do for all other k-apps metadata, if the cloudnative-pg app has no dependencies it can be safely removed from the metadata yaml file. 

Which issue(s) does this PR fix?:

https://jira.nutanix.com/browse/NCN-105607

Special notes for your reviewer:

Does this PR introduce a user-facing change?:

Checklist

• If the PR adds a version bump, ensure there is no breaking change in Licensing model (or NA).
• If a chart is changed or app configuration is significantly changed, the chart version is correctly incremented (so that apps are not automatically upgraded from a previous version of DKP).