[Test] Tests now default to using "Set" battle style

[DayKev]

What are the changes the user will see?

N/A

Why am I making these changes?

Make it easier to write tests.

What are the changes from a developer perspective?

By default, all tests now run in "set" battle style rather than "switch". This can be changed via game.settings.battleStyle = BattleStyle.SWITCH;

How to test the changes?

npm run test

Checklist

• I'm using beta as my base branch
• There is no overlap with another PR?
• The PR is self-contained and cannot be split into smaller PRs?
• Have I provided a clear explanation of the changes?
• [ ] Have I considered writing automated tests for the issue?
• [ ] If I have text, did I add placeholders for them in locales?
• Have I tested the changes (manually)?
  • Are all unit tests still passing? (npm run test)
• [ ] Are the changes visual?
  • [ ] Have I provided screenshots/videos of the changes?

[Tempo-anon]

No user facing changes :snoremax: