minor #12645 [Hackday] [2.7] Add a deprecation note about RegisterListenersPass (jzawadzki)

This PR was squashed before being merged into the 2.7 branch (closes #12645).

Discussion
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[Hackday] [2.7] Add a deprecation note about RegisterListenersPass

| Q             | A
| ------------- | ---
| Fixed tickets | #12633
| License       | MIT

Commits
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9938179 [Hackday] [2.7] Add a deprecation note about RegisterListenersPass

Author: fabpot

DependencyInjection/RegisterListenersPass.php

@@ -11,6 +11,8 @@
 
 namespace Symfony\Component\HttpKernel\DependencyInjection;
 
+trigger_error('Class "Symfony\Component\HttpKernel\DependencyInjection\RegisterListenersPass" is deprecated since 2.5 and will be removed in 3.0. Use "Symfony\Component\EventDispatcher\DependencyInjection\RegisterListenersPass" instead.', E_USER_DEPRECATED);
+
 use Symfony\Component\EventDispatcher\DependencyInjection\RegisterListenersPass as BaseRegisterListenersPass;
 
 /**