Resolve #3473082 "Unnecessary validate in"

Closes #3473082

src/Plugin/Field/FieldWidget/PluginReferenceConfigurationFormTrait.php

@@ -281,6 +281,11 @@ trait PluginReferenceConfigurationFormTrait {
    *   The form where the configuration settings form is being included in.
    */
   public function configurationValidate(array $element, FormStateInterface $form_state, array $form): void {
+    $triggering_element = $form_state->getTriggeringElement();
+    if ($triggering_element['#type'] != 'submit') {
+      return;
+    }
+
     $plugin_manager = $this->getPluginTypeHelper()->getPluginManager($element['#target_type']);
 
     $values = $form_state->getValues();