ref(css): removed list-group mixins (#23138)

src/sentry/static/sentry/less/includes/bootstrap/mixins.less

@@ -17,7 +17,6 @@
 // Components
 @import 'mixins/alerts.less';
 @import 'mixins/buttons.less';
-@import 'mixins/list-group.less';
 @import 'mixins/nav-divider.less';
 @import 'mixins/table-row.less';
 

src/sentry/static/sentry/less/includes/bootstrap/mixins/list-group.less

@@ -1,30 +0,0 @@
-// List Groups
-
-.list-group-item-variant(@state; @background; @color) {
-  .list-group-item-@{state} {
-    color: @color;
-    background-color: @background;
-
-    a&,
-    button& {
-      color: @color;
-
-      .list-group-item-heading {
-        color: inherit;
-      }
-
-      &:hover,
-      &:focus {
-        color: @color;
-        background-color: darken(@background, 5%);
-      }
-      &.active,
-      &.active:hover,
-      &.active:focus {
-        color: #fff;
-        background-color: @color;
-        border-color: @color;
-      }
-    }
-  }
-}