minor #42103 [Form] Remove duplicated array entry (yoannrenard)

This PR was merged into the 5.2 branch.

Discussion
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[Form] Remove duplicated array entry

| Q             | A
| ------------- | ---
| Branch?       | 5.4
| Bug fix?      | no
| New feature?  | no
| Deprecations? | no
| Tickets       | N/A
| License       | MIT
| Doc PR        | N/A

This PR cleans the DateTimeTypeTest test class from a duplicated array entry.

Commits
-------

86ccfa71a1 Remove duplicated array entry

src/Symfony/Component/Form/Tests/Extension/Core/Type/DateTimeTypeTest.php

@@ -523,7 +523,6 @@ class DateTimeTypeTest extends BaseTypeTest
     public function testSingleTextWidgetWithCustomNonHtml5Format()
     {
         $form = $this->factory->create(static::TESTED_TYPE, new \DateTime('2019-02-13 19:12:13'), [
-            'html5' => false,
             'widget' => 'single_text',
             'date_format' => \IntlDateFormatter::SHORT,
             'format' => null,