[New Feature]: Dynamic rounds with no roundstart antagonists shouldn't happen.

[PowerfulBacon]

Describe the feature request

Dynamic should have at least 1 roundstart execution, if there is one possible; even on low threat levels. Extended is specifically disabled, but not picking any roundstart rulesets is only slightly less bad than setting the global threat level to 0 entirely.

Idea:

• Extended forces no roundstart rulesets instead of consuming all the threat. (Midrounds still spawn). Extended remains disabled in the config and can be used for downstreams that might want it.
• Dynamic is forced to pick at least 1 roundstart ruleset. For servers that want extended, extended will be the replacement for not picking any roundstart rulesets.