Improve ABM tests

[reneSchm]

Motivation / Current Behaviour

The current ABM coverage is okay, but some of the tests need to be improved. Most importantly, many tests do not have a clear test case.

Enhancement description

The steps might be:

1. Find out the test case for each test and document it.
2. Decide whether to keep the test, or remove/extend/split it

Additional context

No response

Checklist

• Attached labels, especially loc:: or model:: labels.
• Linked to project

[reneSchm]

Examples:

• TestWorld.evolveMigration is huge, and contains several test cases. It should be split up.
• Several tests in TestMigrationRules use rng without mocking.
• We could think about adding fuzzing or more test cases to some setter/getter tests like TestPerson.setGetAssignedLocation, as they mostly test only one value.

[khoanguyen-dev]

We also need to add all checks for different VirusVariants in check_constraints() of parameters.h