fix dotnet#12818 : Keyboard tooltip of item in toolStrip2 is not disp…

…layed after expanded and collapsed the toolStripDropDownbutton in toolStrip1, then tab to toolStrip2's item

fix dotnet#12819 : Keyboard tooltip of toolStripDropDownbutton in toolStrip1 is displayed after expanded and collapsed the toolStripDropDownbutton in toolStrip2

src/System.Windows.Forms/src/System/Windows/Forms/Controls/ToolStrips/ToolStrip.cs

@@ -3286,7 +3286,7 @@ protected override void OnLostFocus(EventArgs e)
     {
         base.OnLostFocus(e);
         ClearAllSelections();
-        ToolTip.Hide(this);
+        ToolTip.RemoveAll();
     }
 
     protected internal override void OnLeave(EventArgs e)