Revert PPO tanh-normal

[belerico]

Summary

Revert commit fb6f8e3 and the one before

Type of Change

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• Bug fix (non-breaking change that solves an issue)

Checklist

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• I have tested my changes locally and they work as expected. (Please describe the tests you performed.)
• I have added unit tests for my changes, or updated existing tests if necessary.
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