"Click and drag to move" tooltip should not be shown in read-only mode

[Lyuba]

Steps to reproduce

1. Setup editor with widgets plugin in read-only mode
2. Hover over content that renders as a widget

Expected result

No hint text to drag and drop the widget since I cannot do that in read-only mode.

Actual result

I can see the drag target in the top-left corner and its tooltip but it doesn't do anything, so it's just confusing

Other details (browser, OS, CKEditor version, installed plugins)

[Piotrek Koszuliński]

Note to @jswiderski: Widgets are not compatible with the read-only mode. There's a more general ticket somewhere and this one will be its part.

[Jakub Ś]

DUP of #12134