[#4993] Change TestMeasurementGroupConfig.addGroup to deterministic implementation

[anthonyx24]

Issue: See #4993. To summarize, since the groups HashMap is unordered, using Matchers.contains, which does strict order checking, can result in a test failure since the key iteration order isn't guaranteed.

Fix: I simply replace Matchers.contains with Matchers.containsInAnyOrder, since it doesn't do strict order checking.

PR Checklist:

• Github Issue: [BUG] - Nondeterminism in TestMeasurementGroupConfig due to strict order checking of keys in an unordered HashMap #4993
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