Compatibility is really something you care about in a production
setup. Implicit party allocation is a development feature and not
available on most ledgers. Therefore, this PR switches the tests over
to allocate parties explicitly. For sandbox-next we also disable the
implicit party allocation feature completely which allows us to
include the ClosedWorldIT test. Sadbonx-classic does not allow
disabling it atm.

In principle, we could run in both configurations but I don’t think
the additional costs (we have hundreds of those tests and this would
double the number) are worth it due to the same reasons that I’ve
given at the beginning for why explicit allocation is more important.

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• Include appropriate tests
• Set a descriptive title and thorough description
• Add a reference to the issue this PR will solve, if appropriate
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• Normal production system change, include purpose of change in description

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