Eet: Use medium quality for ETC1 by default

And remove  dithering.
This is the same as  07700a799c

src/lib/eet/eet_image.c

@@ -1018,8 +1018,11 @@ eet_data_image_etc1_compressed_convert(int         *size,
 
    nw = htonl(w);
    nh = htonl(h);
-   param.m_dithering = 1;
-   if (quality > 70)
+
+   // Disable dithering, as it will deteriorate the quality of flat surfaces
+   param.m_dithering = 0;
+
+   if (quality > 95)
      {
         param.m_quality = rg_etc1_high_quality;
         block = 7;