The test function for the serializer plugin is called many times (from jest docs)

Pay attention to efficiency in test because pretty-format calls it often.
https://github.com/jestjs/jest/tree/main/packages/pretty-format#test

Using the serializer for many elements causes a large slowdown due to the fact it constructs a large regex every time it's called

I believe this can be improved because

1. Both DEBUG_RESET_CLASSES and DEFINITION_LOOKUP_TABLE are maps so we should be able to lookup a class without doing a string search
2. classes will always be space separated in the string, so we can split the string by spaces to isolate individual classes

This PR changes the test function to use a faster implementation
Simple benchmark test - https://jsperf.app/nevedi