feat: added new tests to profit dist

[bufander]

Description

Added some tests:

• profit no buffer
• profit with buffer
• loss no buffer
• loss with buffer
• loss with not enough buffer

Checklist

• [x] I have run vyper and solidity linting
• [x] I have run the tests on my machine
• [x] I have followed commitlint guidelines
• [x] I have rebased my changes to the latest version of the main branch

[bufander]

Still missing tests with refunds and fees

[jmonteer]

pending tests for refunds