CI, Scripts: Create packages with Octez only

Context

The release pipeline create tarball and link them in the release. The goal of this merge request is to make this tarball contain only the part of the repo that actually belongs to Octez.

It introduces a script that adds to .gitattributes everything that shouldn't be included. This gitattributes are used by git archive to create the Octez tarball.

Manually testing the MR

See https://gitlab.com/nomadic-labs/tezos/-/releases/v1111.35 and the associated dummy release

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