Update public setUp functions in tests to be protected

Problem/Motivation

There are 29 instances of public function setUp(): void in core tests that should be protected.

Steps to reproduce

$ grep -r "public function setUp()" core
core/tests/Drupal/KernelTests/Core/StreamWrapper/ExtensionStreamTest.php:  public function setUp(): void {
core/tests/Drupal/KernelTests/Core/Entity/Sql/SqlContentEntityStorageTest.php:  public function setUp(): void {
core/tests/Drupal/KernelTests/Core/Test/SimpletestTestRunResultsStorageTest.php:  public function setUp(): void {
core/tests/Drupal/KernelTests/Core/Test/TestRunTest.php:  public function setUp(): void {
core/tests/Drupal/KernelTests/Core/Datetime/Element/DatetimeFormElementTest.php:  public function setUp(): void {
core/tests/Drupal/KernelTests/Core/Datetime/DatetimeElementFormTest.php:  public function setUp(): void {
core/tests/Drupal/Tests/Core/Render/Element/ProceduralApiDeprecationTest.php:  public function setUp(): void {
core/tests/Drupal/Tests/Core/Theme/Icon/Plugin/SvgSpriteExtractorTest.php:  public function setUp():void {
core/tests/Drupal/Tests/Core/Theme/Icon/Plugin/PathExtractorTest.php:  public function setUp():void {
core/tests/Drupal/Tests/Core/Theme/Icon/Plugin/SvgExtractorTest.php:  public function setUp():void {
core/tests/Drupal/Tests/Core/Test/WebAssertTest.php:  public function setUp(): void {
core/tests/Drupal/Tests/Core/Session/AccessPolicyProcessorTest.php:  public function setUp(): void {
core/modules/system/tests/src/Functional/Menu/LinksetControllerTest.php:  public function setUp(): void {
core/modules/system/tests/src/Functional/Menu/LinksetControllerMultiLingualTest.php:  public function setUp(): void {
core/modules/system/tests/src/Kernel/ModuleAdminLinksHelperTest.php:  public function setUp(): void {
core/modules/system/tests/src/Kernel/Theme/ThemeHookTest.php:  public function setUp(): void {
core/modules/system/tests/src/Unit/Mail/HtmlToTextTest.php:  public function setUp(): void {
core/modules/user/tests/src/Functional/UserRegistrationRestTest.php:  public function setUp(): void {
core/modules/user/tests/src/Kernel/ModulePermissionsLinkHelperTest.php:  public function setUp(): void {
core/modules/announcements_feed/tests/src/FunctionalJavascript/AlertsJsonFeedTest.php:  public function setUp():void {
core/modules/announcements_feed/tests/src/FunctionalJavascript/AccessAnnouncementTest.php:  public function setUp():void {
core/modules/announcements_feed/tests/src/Unit/AnnounceFetcherUnitTest.php:  public function setUp():void {
core/modules/block_content/tests/src/Kernel/BlockContentPermissionsTest.php:  public function setUp(): void {
core/modules/block_content/tests/src/Kernel/BlockContentTest.php:  public function setUp(): void {
core/modules/block_content/tests/src/Kernel/BlockContentRevisionsTest.php:  public function setUp(): void {
core/modules/views_ui/tests/src/FunctionalJavascript/FilterEntityReferenceTest.php:  public function setUp(): void {
core/modules/workspaces/tests/src/FunctionalJavascript/WorkspacesMediaLibraryIntegrationTest.php:  public function setUp(): void {
core/modules/jsonapi/tests/src/Functional/CommentExtrasTest.php:  public function setUp(): void {
core/modules/jsonapi/tests/src/Functional/ConfigEntityResourceTestBase.php:  public function setUp(): void {

Proposed resolution

Make them all protected to match the visibility of this method in their base classes.

Remaining tasks

User interface changes

Introduced terminology

API changes

Data model changes

Release notes snippet