Remove unnecessary json dumps/loads from tests

Tests used json dumps/loads to make sure each one will have a
separate copy of test data instead of pointer to original one.
Refactored this so now we have utility methods that return new
instance of test data each time.

Change-Id: I2306ba120fd61ede47e2762d910e004e66d6ce7f
Merge "Remove unnecessary json dumps/loads from tests"