Serialize the CI

Building Deimos takes up too many resources to run two build jobs at the same time. Therefore I added new stages for the CentOS 7 and 8 build respectively, disabling the Authorisation build because that is rather unimportant anyway.

Changelog:
* Separate test CI stages for CentOS 7 and 8
* Disable 'Authorisation Disabled' test
5 jobs for serialize_ci in 25 minutes and 33 seconds (queued for 3 seconds)
Status Name Job ID Coverage
  Static Analysis
passed Format #9544
docker

00:01:26

passed Lint #9545
docker

00:07:50

 
  Build
passed Documentation #9546
docker

00:03:42

 
  Test 8
passed Default #9547
docker

00:05:07

 
  Test 7
passed Centos7 #9548
docker

00:08:53