Multiple changes to create current c8s repos on GitLab

[TomasTomecek]

sources: some are located on a different branch than c8s

e.g. ltrace and wireshark are located on c8 instead of c8s

remove .gitlab-ci.yml config from upstream sources

so that CentOS Stream GitLab CI is not being triggered.

make packit.yaml pretty

* no '&' anchors

* no {path: ..., url: ...}, instead we have a block

packit.yaml: set target to centos-stream-8-x86_64

centos-stream-x86_64 is no longer a thing in mock and soon won't even
work in copr

git: favour config file over `git config --system`

We were doing two and now it's just one.

Use our official identify for CentOS Stream GitLab.

[softwarefactory-project-zuul[bot]]

Build failed.

• pre-commit : FAILURE in 1m 57s
• dist2src-tests : FAILURE in 45m 58s
• dist2src-deployment-tests : RETRY_LIMIT in 1h 00m 24s

[softwarefactory-project-zuul[bot]]

Build failed.

• pre-commit : SUCCESS in 2m 23s
• dist2src-tests : FAILURE in 26m 18s
• dist2src-deployment-tests : RETRY_LIMIT in 1h 00m 35s

[softwarefactory-project-zuul[bot]]

Build failed.

• pre-commit : SUCCESS in 2m 08s
• dist2src-tests : SUCCESS in 25m 52s
• dist2src-deployment-tests : RETRY_LIMIT in 1h 00m 30s

[TomasTomecek]

merging, let's try to sort out the image build problem in a dedicated PR