Rely on `symfony/deprecation-contracts` for deprecations

**Is your feature request related to a problem? Please describe.**
Current deprecations use a code like this:

https://github.com/liip/LiipFunctionalTestBundle/blob/8c9176666cd70bb0c5fc2e10a9d77f8136f6a851/src/Test/WebTestCase.php#L282

**Describe the solution you'd like**

- [ ] https://github.com/symfony/deprecation-contracts could be used instead.

- [ ] Consider adding more deprecations if Symfony has built-in helpers that replace the ones from this bundle:
- if it requires a minimal version that is higher than the minimal version required by this bundle
- then *throw* a deprecation only if this version constraint is fulfilled by the project

**Describe alternatives you've considered**
.

**Additional context**
.