[MM-52969] Revert "MM-51482_Create Apps Category and link to bots DM (#22918)" (#23647)

* Revert "MM-51482_Create Apps Category and link to bots DM (#22918)"

This reverts commit 1051925eec.

* Revert "MM-51711_Feature flag: APPS sidebar category (#22766)"

This reverts commit 9156205178.

server/channels/app/team.go

@@ -956,11 +956,9 @@ func (a *App) JoinUserToTeam(c request.CTX, team *model.Team, user *model.User,
 		return nil, model.NewAppError("JoinUserToTeam", "app.user.update_update.app_error", nil, "", http.StatusInternalServerError).Wrap(err)
 	}
 
-	appsCategoryEnabled := a.Config().FeatureFlags.AppsSidebarCategory
 	opts := &store.SidebarCategorySearchOpts{
-		TeamID:              team.Id,
-		ExcludeTeam:         false,
-		AppsCategoryEnabled: appsCategoryEnabled,
+		TeamID:      team.Id,
+		ExcludeTeam: false,
 	}
 	if _, err := a.createInitialSidebarCategories(user.Id, opts); err != nil {
 		mlog.Warn(