MM-16579 Migrate User.GetChannelGroupUsers to Sync by default (#11412)

* Migrate User.GetChannelGroupUsers to Sync by default

* Directly return Store results

app/user.go

@@ -618,11 +618,7 @@ func (a *App) GetTeamGroupUsers(teamID string) ([]*model.User, *model.AppError)
 
 // GetChannelGroupUsers returns the users who are associated to the channel via GroupChannels and GroupMembers.
 func (a *App) GetChannelGroupUsers(channelID string) ([]*model.User, *model.AppError) {
-	result := <-a.Srv.Store.User().GetChannelGroupUsers(channelID)
-	if result.Err != nil {
-		return nil, result.Err
-	}
-	return result.Data.([]*model.User), nil
+	return a.Srv.Store.User().GetChannelGroupUsers(channelID)
 }
 
 func (a *App) GetUsersByIds(userIds []string, asAdmin bool, viewRestrictions *model.ViewUsersRestrictions) ([]*model.User, *model.AppError) {