[11.x] Add CI_DEBUG_SERVICES to 11.x jobs to investigate DB failures

Problem/Motivation

It's been reported both in core and contrib that some test jobs fail due to DB not being available (?)

Core

PHPUnit

https://git.drupalcode.org/issue/drupal-1959304/-/jobs/573143
https://git.drupalcode.org/project/address/-/jobs/616657

Nightwatch

https://git.drupalcode.org/issue/drupal-3324560/-/jobs/629098

Contrib

https://git.drupalcode.org/project/cdn/-/pipelines/75330

Steps to reproduce

Proposed resolution

Add CI_DEBUG_SERVICES=true to .gitlab-ci.yml so we can get detailed information on what's happening in the database from a test that will fail.
Revert the change as soon as we find one job that will fail due to this

Remaining tasks

User interface changes

API changes

Data model changes

Release notes snippet