DEV: Remove group-members-dropdown (#11948)

It was introduced in c82b2dcc24, but since b76731d722 and 58ee947b35 it's a single-option dropdown, so there's no need to show it (and keep it) instead of a button. We use a button for non-admins already.

app/assets/javascripts/discourse/app/templates/mobile/group-index.hbs

@@ -8,19 +8,12 @@
 
   <div class="group-members-manage">
     {{#if canManageGroup}}
-      {{#if currentUser.admin}}
-        {{group-members-dropdown
-          groupName=model.full_name
-          showAddMembersModal=(route-action "showAddMembersModal")
-        }}
-      {{else}}
-        {{d-button
-          icon="plus"
-          label="groups.manage.add_members"
-          class="group-members-add"
-          action=(route-action "showAddMembersModal")
-        }}
-      {{/if}}
+      {{d-button
+        icon="plus"
+        label="groups.manage.add_members"
+        class="group-members-add"
+        action=(route-action "showAddMembersModal")
+      }}
     {{/if}}
   </div>
 

app/assets/javascripts/select-kit/addon/components/group-members-dropdown.js

@@ -1,30 +0,0 @@
-import { action, computed } from "@ember/object";
-import DropdownSelectBoxComponent from "select-kit/components/dropdown-select-box";
-import I18n from "I18n";
-
-export default DropdownSelectBoxComponent.extend({
-  classNames: ["group-members-dropdown"],
-
-  selectKitOptions: {
-    icon: "bars",
-    showFullTitle: false,
-  },
-
-  content: computed(function () {
-    const items = [
-      {
-        id: "showAddMembersModal",
-        name: I18n.t("groups.add_members.title", {
-          group_name: this.groupName,
-        }),
-        icon: "user-plus",
-      },
-    ];
-    return items;
-  }),
-
-  @action
-  onChange(id) {
-    this.attrs && this.attrs[id] && this.attrs[id]();
-  },
-});