Revert "Issue #2938842 by digitaldonkey, martin107: #edit-submit is brittle use the BEM convention"

This reverts commit 0ea9fe97.

core/modules/search/src/Form/SearchBlockForm.php

@@ -108,7 +108,6 @@ public function buildForm(array $form, FormStateInterface $form_state) {
     $form['actions'] = ['#type' => 'actions'];
     $form['actions']['submit'] = [
       '#type' => 'submit',
-      '#id' => 'search-form--submit',
       '#value' => $this->t('Search'),
       // Prevent op from showing up in the query string.
       '#name' => '',

core/modules/settings_tray/tests/src/FunctionalJavascript/SettingsTrayBlockFormTest.php

@@ -183,7 +183,7 @@ public function getBlockTests() {
           'theme' => $theme,
           'block_plugin' => 'search_form_block',
           'new_page_text' => NULL,
-          'element_selector' => '#search-form--submit',
+          'element_selector' => '#edit-submit',
           'label_selector' => 'h2',
           'button_text' => 'Save Search form',
           'toolbar_item' => NULL,