minor #16160 [FrameworkBundle] Deprecate the security.secure_random service (nicolas-grekas)

This PR was merged into the 2.8 branch.

Discussion
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[FrameworkBundle] Deprecate the security.secure_random service

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

Since the SecureRandom class and interface are already deprecated, so should be the service.

Commits
-------

8b55520 [FrameworkBundle] Deprecate the security.secure_random service

src/Symfony/Bundle/FrameworkBundle/Resources/config/security.xml

@@ -14,6 +14,7 @@
             <tag name="monolog.logger" channel="security" />
             <argument>%kernel.cache_dir%/secure_random.seed</argument>
             <argument type="service" id="logger" on-invalid="ignore" />
+            <deprecated>The "%service_id%" service is deprecated since Symfony 2.8 and will be removed in 3.0. Use the random_bytes() function instead.</deprecated>
         </service>
     </services>
 </container>

src/Symfony/Bundle/FrameworkBundle/Tests/DependencyInjection/FrameworkExtensionTest.php

@@ -69,6 +69,7 @@ abstract class FrameworkExtensionTest extends TestCase
         $this->assertTrue($container->hasDefinition('security.csrf.token_manager'));
     }
 
+    /** @group legacy */
     public function testSecureRandomIsAvailableIfCsrfIsDisabled()
     {
         $container = $this->createContainerFromFile('csrf_disabled');