RDS instances not do not show up in aws databases command

[sethsec]

This happened in this commit: 59afbb3

I was trying to remove duplicates where clusters and instances were both showing up, but forgot that you can have an instance WITHOUT a cluster and by moving to only checking for clusters created a situation where instances were missed.

Need to either revert back to using instances only, or grab both clusters AND instances and de-dup them or make it more clear that some are clusters and some are instances.