message: [CRUD] disable user change slices from dashboardmodelview
diff: @@ -530,9 +530,9 @@ class DashboardModelView(SupersetModelView, DeleteMixin): # noqa
  list_columns = ['dashboard_link', 'creator', 'modified']
  order_columns = ['modified']
  edit_columns = [
  - 'dashboard_title', 'slug', 'slices', 'owners', 'position_json', 'css',
  + 'dashboard_title', 'slug', 'owners', 'position_json', 'css',
  'json_metadata']
  - show_columns = edit_columns + ['table_names']
  + show_columns = edit_columns + ['table_names', 'slices']
  search_columns = ('dashboard_title', 'slug', 'owners')
  add_columns = edit_columns
  base_order = ('changed_on', 'desc')
  @@ -555,10 +555,6 @@ class DashboardModelView(SupersetModelView, DeleteMixin): # noqa
  'owners': _('Owners is a list of users who can alter the dashboard.'),
  }
  base_filters = [['slice', DashboardFilter, lambda: []]]
  - add_form_query_rel_fields = {
  - 'slices': [['slices', SliceFilter, None]],
  - }
  - edit_form_query_rel_fields = add_form_query_rel_fields
  label_columns = {
  'dashboard_link': _('Dashboard'),
  'dashboard_title': _('Title'),
  