fix(button-group): fix button group colors in selected state

Author: didimmova

projects/igniteui-angular/core/src/core/styles/components/button-group/_button-group-theme.scss

@@ -245,7 +245,7 @@
 
         &[igxButton].igx-button--focused {
             background: var-get($theme, 'item-selected-focus-background');
-            border-color: var-get($theme, 'item-selected-hover-border-color');
+            border-color: var-get($theme, 'item-selected-border-color');
             color: var-get($theme, 'item-selected-text-color');
 
             igx-icon {
@@ -261,7 +261,6 @@
             }
 
             @if $variant == 'indigo' {
-                border-color: var-get($theme, 'item-selected-border-color');
                 box-shadow: 0 0 0 rem(3px) var-get($theme, 'selected-shadow-color');
             }
 
@@ -276,15 +275,11 @@
                 igx-icon {
                     color: var-get($theme, 'item-selected-hover-icon-color');
                 }
-
-                @if $variant == 'indigo' {
-                    border-color: var-get($theme, 'item-selected-hover-border-color');
-                }
             }
 
             &:hover {
                 background: var-get($theme, 'item-selected-focus-hover-background');
-                border-color: var-get($theme, 'item-selected-border-color');
+                border-color: var-get($theme, 'item-selected-hover-border-color');
             }
 
             &:active {