BButton: Remove button label margins

... to prevent label truncation on BeControlLook,
BDH Calc, and some other places.

Fixes #16570

Change-Id: I68d8b64a631e116d3180c96be1fb5681de86fda6
Reviewed-on: https://review.haiku-os.org/c/haiku/+/6310
Tested-by: Commit checker robot <no-reply+buildbot@haiku-os.org>
Reviewed-by: Adrien Destugues <pulkomandy@pulkomandy.tk>

src/kits/interface/Button.cpp

@@ -155,10 +155,6 @@ BButton::Draw(BRect updateRect)
 			base, flags);
 	}
 
-	// always leave some room around the label
-	float labelMargin = be_control_look->DefaultLabelSpacing() / 2;
-	rect.InsetBy(labelMargin, labelMargin);
-
 	const BBitmap* icon = IconBitmap(
 		(Value() == B_CONTROL_OFF
 				? B_INACTIVE_ICON_BITMAP : B_ACTIVE_ICON_BITMAP)