packages: fix fedora systemd tests

What

This MR fix a problem related to the systemd tests.

This job fails because the systemd tests Dockerfile was not general enough to run also tests for fedora. https://gitlab.com/nomadic-labs/tezos/-/jobs/9160274959

This MR fix this problem.

Why

How

I generalize the Dockerfile and fix the CIAO pipelines related to systemd tests.

I added ARG IMAGE=invalid to avoid a docker warning.

Manually testing the MR

I run this scheduled pipeline : https://gitlab.com/nomadic-labs/tezos/-/pipelines/1676477120

check if all systemd tests are not correctly executed.

To test locally : ``DISTRIBUTION=fedora RELEASE=39 scripts/packaging/tests/systemd-docker-test.sh scripts/packaging/tests/rpm/rpm-install.sh images/packages/rpm-systemd-tests.Dockerfile```

( notice that depending on the speed of your machine/network, this test might fail because of a timeout. )

Checklist

• Document the interface of any function added or modified (see the coding guidelines)
• Document any change to the user interface, including configuration parameters (see node configuration)
• Provide automatic testing (see the testing guide).
• For new features and bug fixes, add an item in the appropriate changelog (docs/protocols/alpha.rst for the protocol and the environment, CHANGES.rst at the root of the repository for everything else).
• Select suitable reviewers using the Reviewers field below.
• Select as Assignee the next person who should take action on that MR