Should scripts/*.sh files be executable?
No. You don't need to execute permissions on those scripts in a production server environment.
The only reason you'd need those scripts executable on a server is for running code testing utilities (e.g. simpletest test cases, generating dummy content, etc.) on the codebase. Unless you're wanting to run some of those testing utilities on a CI server, they don't need to be executable for Drupal to work.