Revert "Fix initialism errors (PR-3) (#17062)" (#17202)

This reverts commit ea61458f16. This was causing panic in the plugins because the client and the plugin API changed with this PR

app/group.go

@@ -65,7 +65,7 @@ func (a *App) GetGroupsBySource(groupSource model.GroupSource) ([]*model.Group,
 	return groups, nil
 }
 
-func (a *App) GetGroupsByUserID(userID string) ([]*model.Group, *model.AppError) {
+func (a *App) GetGroupsByUserId(userID string) ([]*model.Group, *model.AppError) {
 	groups, err := a.Srv().Store.Group().GetByUser(userID)
 	if err != nil {
 		return nil, model.NewAppError("GetGroupsByUserId", "app.select_error", nil, err.Error(), http.StatusInternalServerError)