CI: reset FF_KUBERNETES_HONOR_ENTRYPOINT = false

Context

This MR fix a few scripts to be able to use the GCP default of FF_KUBERNETES_HONOR_ENTRYPOINT=false

This mainly entails adding eval $(opam env) in a few scripts and jobs.

I set a global env variable to false, but the correct fix, it to remove this customization from the kuberneties chart used to deploy the runner. This can be done after merging this MR with the next redeployment.

The default on gitlab is to false for this variable ( https://docs.gitlab.com/runner/configuration/feature-flags.html#available-feature-flags ) . Here I'm trying to restore this default. This implies adapting our scripts.

Manually testing the MR

Test if a pipeline completes successfully.

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