Remove deploymentName label on every ScaledObject

[tomkerkhove]

In #504 we've fixed an issue where we correctly log the missing deploymentName label on every ScaledObject.

However, do we still need the label? If so, what was the reason again?

Ideally, we get rid of this as it's duplicated data from spec.scaleTargetRef.deploymentName which is not ideal.

[tomkerkhove]

If we cannot remove it, I'll add a section on https://keda.sh/faq for it

[ppatierno]

@tomkerkhove to be honest I don't see any reason for leaving that label.
As far as I can see the entire rest of the logic leverages on the spec.scaleTargetRef.
If we agree to remove it, I am happy to help on this with a PR.

[tomkerkhove]

Yes, was somewhat the consensus on #242 but added to agenda for standup before we get things going as a final verification.

[ppatierno]

So from #242 it seems that we can remove the label as mandatory field to be specified by the user but the operator has to add it for the metrics server.

[jeffhollan]

Chatted about this briefly in standup - sounds good. It doesn't sound like there is a downside to doing this

[tomkerkhove]

Are you up for it @ppatierno?

[ppatierno]

Yes, guys, I will take it over the weekend I guess.