Tezt-cloud ssh options cleanup

Here is a followup MR addressing the discussion of #8034 (closed).

It simply introduce placeholders for ssh and scp command options used in the tezt-cloud framework. In addition to that, some commands now rely on the runner.options field that aims to reflect the ssh option that were use to create the runner associated to an agent.

Closes #8034 (closed)

Manually testing the MR

Run the usual dal scenario. It should be noop. I've tested with the following and it worked as expected.

dune exec tezt/tests/cloud/main.exe -- DAL --localhost -v --tezt-cloud dal --producers 1 --log-file experiment.log --retrieve-daily-logs ./experiment_logs

dune exec tezt/tests/cloud/main.exe -- DAL -v --tezt-cloud vicall-dal --dockerfile-alias dal --producers 1 --log-file experiment.log --retrieve-daily-logs ./experiment_logs

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