minor #22894 Remove PHP<7 leftovers (chalasr)
minor #22894 Remove PHP<7 leftovers (chalasr)

This PR was merged into the 4.0-dev branch.

Discussion
----------

Remove PHP<7 leftovers

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

Forgot while cleaning up

Commits
-------

f0147da Remove PHP < 7.1 leftovers

symfony/DependencyInjection,symfony/dependency-injection