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

symfony/HttpKernel,symfony/http-kernel