.../block/tests/src/Functional/BlockTest.php       |  3 +--
 .../block_content_test/block_content_test.install  | 29 ----------------------
 .../src/Functional/BlockContentCreationTest.php    |  8 +++---
 .../config/install/config_test.validation.yml      |  3 +++
 .../system/tests/src/Kernel/Action/ActionTest.php  |  1 -
 5 files changed, 7 insertions(+), 37 deletions(-)

diff --git a/core/modules/block/tests/src/Functional/BlockTest.php b/core/modules/block/tests/src/Functional/BlockTest.php
index 60a43bfbbd..bc6fcded6f 100644
--- a/core/modules/block/tests/src/Functional/BlockTest.php
+++ b/core/modules/block/tests/src/Functional/BlockTest.php
@@ -580,7 +580,6 @@ public function testBlockUserRoleDelete() {
     $block = Block::create([
       'id' => $this->randomMachineName(),
       'plugin' => 'system_powered_by_block',
-      'theme' => 'stark',
     ]);
 
     $block->setVisibilityConfig('user_role', [
@@ -616,7 +615,7 @@ public function testBlockTitle() {
     ];
     // Set the block to be shown only to authenticated users.
     $edit['visibility[user_role][roles][' . RoleInterface::AUTHENTICATED_ID . ']'] = TRUE;
-    $this->drupalGet('admin/structure/block/add/system_powered_by_block/' . $default_theme);
+    $this->drupalGet('admin/structure/block/add/foo/' . $default_theme);
     $this->submitForm($edit, 'Save block');
 
     // Ensure that the title is displayed as plain text.
diff --git a/core/modules/block_content/tests/modules/block_content_test/block_content_test.install b/core/modules/block_content/tests/modules/block_content_test/block_content_test.install
deleted file mode 100644
index 06d47a9645..0000000000
--- a/core/modules/block_content/tests/modules/block_content_test/block_content_test.install
+++ /dev/null
@@ -1,29 +0,0 @@
-<?php
-
-/**
- * @file
- * Install, update and uninstall functions for the block_content_test module.
- */
-
-use Drupal\block_content\Entity\BlockContent;
-use Drupal\block_content\Entity\BlockContentType;
-
-/**
- * Implements hook_module_preinstall().
- */
-function block_content_test_module_preinstall($module) {
-  if ($module === 'block_content_test' && !\Drupal::service('config.installer')->isSyncing()) {
-    // Run before importing config so blocks are created with the correct
-    // dependencies.
-    BlockContentType::create([
-      'id' => 'test',
-      'label' => 'Test',
-    ])->save();
-    BlockContent::create([
-      'type' => 'test',
-      // @see config/install/block.block.foobargorilla.yml
-      'uuid' => 'fb5e8434-3617-4a1d-a252-8273e95ec30e',
-      'info' => 'Something',
-    ])->save();
-  }
-}
diff --git a/core/modules/block_content/tests/src/Functional/BlockContentCreationTest.php b/core/modules/block_content/tests/src/Functional/BlockContentCreationTest.php
index 5d3f7febdf..bd499aa22b 100644
--- a/core/modules/block_content/tests/src/Functional/BlockContentCreationTest.php
+++ b/core/modules/block_content/tests/src/Functional/BlockContentCreationTest.php
@@ -205,19 +205,17 @@ public function testBlockDelete() {
     $this->submitForm($edit, 'Save');
 
     // Place the block.
-    // Note: this is the second block_content entity, the first was created in
-    // block_content_test_module_preinstall().
     $instance = [
       'id' => mb_strtolower($edit['info[0][value]']),
       'settings[label]' => $edit['info[0][value]'],
       'region' => 'sidebar_first',
     ];
-    $block = BlockContent::load(2);
+    $block = BlockContent::load(1);
     $url = 'admin/structure/block/add/block_content:' . $block->uuid() . '/' . $this->config('system.theme')->get('default');
     $this->drupalGet($url);
     $this->submitForm($instance, 'Save block');
 
-    $block = BlockContent::load(2);
+    $block = BlockContent::load(1);
 
     // Test getInstances method.
     $this->assertCount(1, $block->getInstances());
@@ -227,7 +225,7 @@ public function testBlockDelete() {
     $this->assertSession()->pageTextContains($body);
 
     // Delete the block.
-    $this->drupalGet('admin/content/block/2/delete');
+    $this->drupalGet('admin/content/block/1/delete');
     $this->assertSession()->pageTextContains('This will also remove 1 placed block instance.');
 
     $this->submitForm([], 'Delete');
diff --git a/core/modules/config/tests/config_test/config/install/config_test.validation.yml b/core/modules/config/tests/config_test/config/install/config_test.validation.yml
index fa84ff392b..f69841d325 100644
--- a/core/modules/config/tests/config_test/config/install/config_test.validation.yml
+++ b/core/modules/config/tests/config_test/config/install/config_test.validation.yml
@@ -6,3 +6,6 @@ giraffe:
   hum1: hum1
   hum2: hum2
 uuid: '7C30C50E-641A-4E34-A7F1-46BCFB9BE5A3'
+# Required because inherited from `type: config_object`.
+# @see core/config/schema/core.data_types.schema.yml
+langcode: en
diff --git a/core/modules/system/tests/src/Kernel/Action/ActionTest.php b/core/modules/system/tests/src/Kernel/Action/ActionTest.php
index 9bac28f573..becf628e64 100644
--- a/core/modules/system/tests/src/Kernel/Action/ActionTest.php
+++ b/core/modules/system/tests/src/Kernel/Action/ActionTest.php
@@ -34,7 +34,6 @@ protected function setUp(): void {
 
     $this->actionManager = $this->container->get('plugin.manager.action');
     $this->installEntitySchema('user');
-    $this->installConfig(['user']);
     $this->installSchema('system', ['sequences']);
   }