Remove unused group-list-item-out-of-scope.scss component

The corresponding JS component was removed as part of the recent
redesign of the groups menu.

src/styles/sidebar/components/group-list-item-out-of-scope.scss

-/* The group-list out of scope item. */
-
-.group-list-item-out-of-scope {
-  display: flex;
-  flex-direction: row;
-  flex-grow: 1;
-}
-
-.group-list-item-out-of-scope__item {
-  background-color: $gray-lightest;
-  color: $gray-light;
-}
-
-.group-list-item-out-of-scope__icon--unavailable {
-  fill: $gray-light;
-  float: right;
-  height: 20px;
-  width: auto;
-}
-
-.group-list-item-out-of-scope__details {
-  flex-grow: 1;
-  flex-shrink: 1;
-  font-weight: 500;
-}
-
-.group-list-item-out-of-scope__details-toggle {
-  font-size: $body1-font-size;
-  font-style: italic;
-  margin: 0;
-  text-decoration: underline;
-}
-
-.group-list-item-out-of-scope__details-unavailable-message {
-  font-size: $body1-font-size;
-  line-height: 1.5;
-  white-space: normal;
-  width: $group-list-width - 60px;
-}
-
-.group-list-item-out-of-scope__details-actions {
-  text-align: right;
-}
-
-.group-list-item-out-of-scope__details-group-page-link {
-  color: inherit;
-  font-size: $body1-font-size;
-  text-decoration: underline;
-  text-transform: uppercase;
-}

src/styles/sidebar/sidebar.scss

@@ -25,7 +25,6 @@ $base-line-height: 20px;
 @import './components/excerpt';
 @import './components/group-list-v2';
 @import './components/group-list-item';
-@import './components/group-list-item-out-of-scope';
 @import './components/help-panel';
 @import './components/loggedout-message';
 @import './components/login-control';