Dont add XML sitemap fields to irrelevant forms.

On entity forms that are not edit or delete, XML sitemap attempts to add its form fields and functionality, resulting in this errors similar to:

Warning: array_unshift() expects parameter 1 to be array, null given in xmlsitemap_add_form_link_options() (line 1256 of modules/contrib/xmlsitemap/xmlsitemap.module).
xmlsitemap_add_form_link_options(Array, 'node', 'test', '1983') (Line: 1580)
xmlsitemap_form_alter(Array, Object, 'node_test_entity_hierarchy_reorder_form') (Line: 539)
Drupal\Core\Extension\ModuleHandler->alter('form', Array, Object, 'node_test_entity_hierarchy_reorder_form') (Line: 834)
Drupal\Core\Form\FormBuilder->prepareForm('node_test_entity_hierarchy_reorder_form', Array, Object) (Line: 276)
Drupal\Core\Form\FormBuilder->buildForm('node_test_entity_hierarchy_reorder_form', Object) (Line: 93)
Drupal\Core\Controller\FormController->getContentResult(Object, Object)
call_user_func_array(Array, Array) (Line: 123)
Drupal\Core\EventSubscriber\EarlyRenderingControllerWrapperSubscriber->Drupal\Core\EventSubscriber\{closure}() (Line: 582)
Drupal\Core\Render\Renderer->executeInRenderContext(Object, Object) (Line: 124)
...

The above error is from an entity form provided by Entity Hierarchy, but is also present for the entity form provided by Scheduled Transitions.

Fix is to make sure XML sitemap doesnt add its fields to forms that return NULL for \Drupal\Core\Form\BaseFormIdInterface::getBaseFormId (see docs).

Patch also changes order of conditions to reduce processing.