Swap order of expected value and actual value when using [assertProto2Equal](https://source.corp.google.com/piper///depot/google3/net/proto2/contrib/pyutil/compare.py;rcl=781699748;l=153) to be consistent with definition.

[copybara-service[bot]]

Swap order of expected value and actual value when using assertProto2Equal to be consistent with definition.

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