Run hydration tests in both static-optimized and non-static-optimized modes

[nolanlawson]

We have some hydration Karma tests that implicitly disable the static content optimization by adding lwc:spread. This is a bit repetative and fragile – it will break if lwc:spread ever becomes static-optimized.

Instead, we should do what we do with the regular Karma tests and have a mode like:

DISABLE_STATIC_CONTENT_OPTIMIZATION=1 yarn hydration:test

This would disable the static content optimization explicitly for all hydration tests.