Revert "Always disable anti-aliasing for drawing cell borders." fdo#60805

Unfortunately this patch creates a very weird ( and took me forever to find
) bug ( fdo#60805 ). Basically certain double line borders seems to
dissappear at certain zoom levels. I guess maybe its possible to tweak
the create2DDecomposition to process the line as hairline at those problematic
zoom levels ( but I suspect that actually would look worse ) Best maybe
would be to tweak the rendering/painting ( but isn't that processor specific
maybe ? ) as is maybe this problem. I admit this is outside my comfort zone :/

This reverts commit a551cad4e35b6b664167d65dfc25e5a0f6990687.

Change-Id: Idb25493ffb038cb1f8ae9b364a29052abafd940d