Fix for force_lever output issues

[chryswoods]

This fixes some bugs that were introduced with feature_force_lever that related to how the lever was printed to the screen. Despite the lever working as expected (hence why tests passed), the lever printed to the screen showing that it had no set levers.

Also, in debugging this, I found an issue in the new functionality where a default lever for a force was not being picked up (i.e. ghost/ghost::* was not taking precedence over, e.g. *::charge)

I've updated the unit tests to catch these edge cases

• I confirm that I have merged the latest version of devel into this branch before issuing this pull request (e.g. by running git pull origin devel): [y]
• I confirm that I have added a changelog entry to the changelog (we will add a link to this PR as part of the review): [N/A]
• I confirm that I have permission to release this code under the GPL3 license: [y]

Suggested reviewers:

@lohedges

Any additional context of information?

This is a minor change to LambdaSchedule. I've not updated the changelog as it this is fixing something introduced in the last PR, which is described in the changelog.

[lohedges]

Thanks for catching this. Looks good 👍