refactor: remove unused styles (#217)

Author: spike-rabbit

projects/ngx-datatable/src/lib/components/datatable.component.scss

@@ -46,12 +46,6 @@
           white-space: nowrap;
           text-overflow: ellipsis;
         }
-
-        .datatable-body-group-cell {
-          overflow: hidden;
-          white-space: nowrap;
-          text-overflow: ellipsis;
-        }
       }
     }
   }

projects/ngx-datatable/src/lib/themes/material.scss

@@ -313,16 +313,6 @@ $datatble-ghost-cell-animation-duration: 10s;
         //  background: #0829e0
         // }
       }
-      .datatable-body-group-cell {
-        text-align: left;
-        padding: 0.9rem 1.2rem;
-        vertical-align: top;
-        border-top: 0;
-        color: $datatable-body-cell-color;
-        transition: width 0.3s ease;
-        font-size: 14px;
-        font-weight: 400;
-      }
     }
 
     .progress-linear {