Avoid fold margin corruption in wxStyledTextCtrl under MSW

Don't use the content scale factor when creating bitmaps in InitPixMap(), this
is wrong and results in badly sized bitmaps at least under MSW (and possibly
GTK too).

Closes #17069.

src/stc/PlatWX.cpp

@@ -257,8 +257,13 @@ void SurfaceImpl::InitPixMap(int width, int height, Surface *surface, WindowID w
     hdcOwned = true;
     if (width < 1) width = 1;
     if (height < 1) height = 1;
+#ifdef __WXMSW__
+    bitmap = new wxBitmap(width, height);
+    wxUnusedVar(winid);
+#else
     bitmap = new wxBitmap();
     bitmap->CreateScaled(width, height,wxBITMAP_SCREEN_DEPTH,((wxWindow*)winid)->GetContentScaleFactor());
+#endif
     ((wxMemoryDC*)hdc)->SelectObject(*bitmap);
 }