Deprecate explicitly setting metricName for all scalers

[yardenshoham]

In v2.12 this setting will be internalized and should not be set by users

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• Commits are signed with Developer Certificate of Origin (DCO)

Docs part of kedacore/keda#4235
Relates to kedacore/keda#4220

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[tomkerkhove]

@JorTurFer @zroubalik Any thoughts on annotating previous version to create awareness on the deprecation?

[JorTurFer]

@JorTurFer @zroubalik Any thoughts on annotating previous version to create awareness on the deprecation?

IDK... I guess that adding the annotation only to the versions where it is deprecated is more consistent. I mean, we have introduced a warning in the code. Let's add the annotation only to versions where the message is logged but I don't have a strong opinion, if @zroubalik agrees with annotating other versions too, go ahead

[zroubalik]

@JorTurFer @zroubalik Any thoughts on annotating previous version to create awareness on the deprecation?

IDK... I guess that adding the annotation only to the versions where it is deprecated is more consistent. I mean, we have introduced a warning in the code. Let's add the annotation only to versions where the message is logged but I don't have a strong opinion, if @zroubalik agrees with annotating other versions too, go ahead

+1 let's keep it simple