docker compose scripts: make them executable (#4590)

## Motivation

docker related scripts didn't have the exec bit enabled

## Proposal

Just make the script executable

## Test Plan

tested locally and on a validator

## Release Plan

- release on main for future needs
- backport to testnet_conway

- [reviewer
checklist](https://github.com/linera-io/linera-protocol/blob/main/CONTRIBUTING.md#reviewer-checklist)

Author: eldios