minor #15624 consistently use str_replace to unify directory separators (2.7) (Tobion)

This PR was merged into the 2.7 branch.

Discussion
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consistently use str_replace to unify directory separators (2.7)

| Q             | A
| ------------- | ---
| Bug fix?      | no
| New feature?  | no
| BC breaks?    | no
| Deprecations? | no
| Tests pass?   | yes
| Fixed tickets |
| License       | MIT
| Doc PR        | -

Remaining ones from #15614

Commits
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17ce649 consistently use str_replace to unify directory separators (remaining)

Author: fabpot

Tests/Functional/SetAclCommandTest.php

@@ -106,7 +106,7 @@ public function testSetAclRole()
         $setAclCommandTester = new CommandTester($setAclCommand);
         $setAclCommandTester->execute(array(
             'command' => 'acl:set',
-            'arguments' => array($grantedPermission, sprintf('%s:%s', strtr(self::OBJECT_CLASS, '\\', '/'), $objectId)),
+            'arguments' => array($grantedPermission, sprintf('%s:%s', str_replace('\\', '/', self::OBJECT_CLASS), $objectId)),
             '--role' => array($role),
         ));