The "Play In" > "Properties Editor" option is not only updating Property
Editors but also the sidebars of other editors (such as the 3DView).
This caused a bit of confusion since we also have "Play In" > "3D
Viewport" (which only updates the 3DView main region but not the
sidebar)
So now call the option "Properties and Sidebars" in the UI ("Editor" has
been stripped to fit the text - but also since the editor is usually
only called "Properties" e.g. in the editor dropdown).
Came up in #120012