minor #47401 Replace get_class() calls by ::class (deguif)

This PR was squashed before being merged into the 6.2 branch.

Discussion
----------

Replace get_class() calls by ::class

| Q             | A
| ------------- | ---
| Branch?       | 6.2
| Bug fix?      | no
| New feature?  | no
| Deprecations? | no
| Tickets       |
| License       | MIT
| Doc PR        |

Replace `get_class()` by `::class`

Commits
-------

675601b8f7 Replace get_class() calls by ::class

Author: fabpot

Tests/ErrorHandlerTest.php

@@ -327,7 +327,7 @@ public function testHandleErrorWithAnonymousClass()
 
         $handler = ErrorHandler::register();
         try {
-            trigger_error('foo '.\get_class($anonymousObject).' bar', \E_USER_WARNING);
+            trigger_error('foo '.$anonymousObject::class.' bar', \E_USER_WARNING);
             $this->fail('Exception expected.');
         } catch (\ErrorException $e) {
         } finally {
@@ -372,7 +372,7 @@ public function testHandleException(string $expectedMessage, \Throwable $excepti
             $logArgCheck = function ($level, $message, $context) use ($expectedMessage, $exception) {
                 $this->assertSame($expectedMessage, $message);
                 $this->assertArrayHasKey('exception', $context);
-                $this->assertInstanceOf(\get_class($exception), $context['exception']);
+                $this->assertInstanceOf($exception::class, $context['exception']);
             };
 
             $logger