[SecurityBundle] Only register CSRF protection listener if CSRF is available

[wouterj]

Q	A
Branch?	5.1
Bug fix?	yes
New feature?	no
Deprecations?	yes
Tickets	Fix #37033
License	MIT
Doc PR	-

I know we're not allowed to add new deprecations in already released versions. However, I don't think anyone is using SecurityBundle's compiler passes except from Symfony itself - so I don't think anyone is affected by this deprecation. The alternatives would be:

• Add a new compiler pass in 5.1 that conditionally registers the CSRF listener
• Do this exact change in 5.2 and...
  • accept a null argument in the listener for 5.1
  • or add this to the RegisterCsrfTokenClearingLogoutHandlerPass class in 5.1

[fabpot]

Thank you @wouterj.