Remove Control z-index warning

[KoBeWi]

Addresses #69895

The warning message now mentions that it can be disabled: is completely gone.

[Geometror]

I'm in favor of providing a way to disable this warning. After reading through #69895 it looks like that a dedicated project setting is justified in this case as many users have strong feelings about the presence of that warning :) Well aware that this isn't the best (permanent) solution, but I think it's the best we can currently do without major/breaking changes to the configuration warning system.

[YeldhamDev]

This feels like a band-aid. It would be better to have a way to silence any warning.

[KoBeWi]

Do you have a specific system in mind for disabling warning though? It was mentioned many times, but no one even opened a proposal so far.

[AThousandShips]

A general control of warning display would be nice, but IMO this is a special case, many other warnings are less relevant to hide (like collision objects without shapes, which isn't really valid, scale warnings, etc.), this one is simply information, rather than something being wrong as such

We might even want to add categories to warnings in the future to distinguish "warnings" from "information", with a white triangle perhaps

[akien-mga]

This feels pretty hacky to me. And since it needs to be configured in the project settings, users who know and don't care to keep being reminded about this will need to disable it manually in every single project they make that users Z index on Controls.

IMO, aside from a more involved system to make configuration warnings more flexible as suggested in godotengine/godot-proposals#9416, this particular one may just need to go. A crystal clear warning in the documentation should be sufficient. We can try, and if we find that too many users are confused, we can add a warning back. But currently we only tried with a warning and thus with users confused by the warning, and not by what it teaches them.

[KoBeWi]

A crystal clear warning in the documentation should be sufficient.

Where though? In z_index description, which is in CanvasItem?

[akien-mga]

A crystal clear warning in the documentation should be sufficient.

Where though? In z_index description, which is in CanvasItem?

Yeah I think so. And maybe a note in the Control description?

[KoBeWi]

I removed the warning. Seems like it's sufficiently documented already.

[akien-mga]

Thanks!