minor symfony#38053 [Form] Remove invalid instantiation declaration (siganushka)

This PR was submitted for the master branch but it was merged into the 4.4 branch instead.

Discussion
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[Form] Remove invalid instantiation declaration

| Q             | A
| ------------- | ---
| Branch?       | master
| Bug fix?      | yes
| New feature?  | no
| Deprecations? | no
| Tickets       | No ticket
| License       | MIT
| Doc PR        | N/A

Remove invalid instantiation declaration

Commits
-------

6e17099 Remove invalid instantiation declaration

Author: fabpot

src/Symfony/Component/Form/Tests/Extension/Core/DataTransformer/StringToFloatTransformerTest.php

@@ -16,18 +16,6 @@
 
 class StringToFloatTransformerTest extends TestCase
 {
-    private $transformer;
-
-    protected function setUp(): void
-    {
-        $this->transformer = new StringToFloatTransformer();
-    }
-
-    protected function tearDown(): void
-    {
-        $this->transformer = null;
-    }
-
     public function provideTransformations(): array
     {
         return [