Revert "feat(units): add more data rate units"

This reverts commit a35bf497bed5553bbce75461ea235c359927e2f4.

public/app/core/utils/kbn.js

@@ -595,10 +595,6 @@ function($, _) {
           {text: 'packets/sec', value: 'pps'},
           {text: 'bits/sec',    value: 'bps'},
           {text: 'bytes/sec',   value: 'Bps'},
-          {text: 'megabytes/sec', value: 'MBs'},
-          {text: 'megabites/sec', value: 'Mbits'},
-          {text: 'gigabytes/sec', value: 'GBs'},
-          {text: 'gigabites/sec', value: 'Gbits'},
         ]
       },
       {