Fix sizing wxBitmapButton used as wxPropertyGrid editor button

Since wxBitmapButton doesn't rescale embedded bitmap we need
to do this on our own to display entire bitmap even the button
is small.

Closes #18715.

src/propgrid/propgrid.cpp

@@ -1331,9 +1331,7 @@ void wxPropertyGrid::CalculateFontAndBitmapStuff( int vspacing )
     GetTextExtent(wxS("jG"), &x, &y, 0, 0, &m_captionFont);
 
     m_lineHeight = m_fontHeight+(2*m_spacingy)+1;
-#if defined(__WXGTK3__)
-    m_lineHeight = wxMax(35, m_lineHeight);
-#endif
+
     // button spacing
     m_buttonSpacingY = (m_lineHeight - m_iconHeight) / 2;
     if ( m_buttonSpacingY < 0 ) m_buttonSpacingY = 0;