minor #11966 [HttpFoundation] fixed some volatile tests (fabpot)

This PR was merged into the 2.3 branch.

Discussion
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[HttpFoundation] fixed some volatile tests

| Q             | A
| ------------- | ---
| Bug fix?      | no
| New feature?  | no
| BC breaks?    | no
| Deprecations? | no
| Tests pass?   | yes
| Fixed tickets | see #11588
| License       | MIT
| Doc PR        | n/a

Commits
-------

00c1b75 [Process] fixed some volatile tests
974bf01 [HttpKernel] fixed a volatile test
6020c43 [HttpFoundation] fixed some volatile tests

Author: fabpot

Tests/HttpCache/HttpCacheTest.php

@@ -606,7 +606,7 @@ public function testAssignsDefaultTtlWhenResponseHasNoFreshnessInformationAndAft
         $this->assertTraceContains('miss');
         $this->assertTraceContains('store');
         $this->assertEquals('Hello World', $this->response->getContent());
-        $this->assertRegExp('/s-maxage=2/', $this->response->headers->get('Cache-Control'));
+        $this->assertRegExp('/s-maxage=(?:2|3)/', $this->response->headers->get('Cache-Control'));
 
         $this->request('GET', '/');
         $this->assertHttpKernelIsNotCalled();