packages: refactor tests scripts and bugfix

What

This MR does a small refactoring of the test scripts to ensure consistency between rpm and deb test.

I fix few minor problems:

• launch also the accuser when invoking the octez-baker service
• fix a minor problem with stopping the octez-baker service
• Honor the custom data dir in the octez-baker service
• use execstart instead of execprestart in the systemd service
• add back /etc/default/octez-accuser file that was removed by mistake.

Why

Better QA for packages and avoid failures like :

https://gitlab.com/tezos/tezos/-/jobs/9369097273

How

I factored out some shell functions and added back as "include".

The only modification is the use of wait-for-node.sh in the rpm test to reduce flakiness.

Manually testing the MR

check if all tests pass as before.

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

Summary by CodeRabbit

• New Features

  • Added common utilities to enhance package management reliability and system service testing.

• Refactor

  • Streamlined installation and upgrade scripts by replacing custom retry and service management logic with centralized implementations.
  • Adjusted command execution to remove unnecessary privilege escalations.

• Tests

  • Updated container image configurations to include new testing utilities, ensuring improved diagnostics and validation for systemd services.