remove \Drupal::logger call in Negotiator.php

Problem/Motivation

phpstan reports:

------ ------------------------------------------------------------------------------
Line src/Negotiator.php
------ ------------------------------------------------------------------------------
85 \Drupal calls should be avoided in classes, use dependency injection instead
------ ------------------------------------------------------------------------------

However, the code already has $this->logger() defined.

Steps to reproduce

phpstan analyse consumers

Proposed resolution

Use the injected dependency instead of calling the static function.

Remaining tasks

Make an MR.