I have tried the described scenario and it works as expected. There is no borders on data cells and above the pager. However you can achieve the same thing with one CSS rule and without !important, e.g.
div.RadGrid_Metro .rgRow td,
div.RadGrid_Metro .rgAltRow td,
You can find attached screenshot on what is on my side.
Hope this helps.
All the best,
the Telerik team
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