fix(og): N-04 - Eliminate redundant code

[Reinis-FRP]

Motivation

OZ identified the following issue:

Consider making the following changes to eliminate redundant code:
• In OptimisticGovernor.sol , msg.sender is used on line 263 to transfer tokens
from the proposer to the Optimistic Governor contract, but proposer has already been
defined as msg.sender on line 234, so proposer can be used here.
• In OptimisticGovernor.sol , line 310 computes the assertionId , but this value
was already computed on line 307 inside a require statement. Lines 310 and 307 can
be swapped, and proposalHashes[_proposalhash] inside the require
statement can be replaced with assertionId .

Summary

This PR addresses this issue by implementing suggested fixes above.

Testing

Check a box to describe how you tested these changes and list the steps for reviewers to test.

• Ran end-to-end test, running the code as in production
• New unit tests created
• Existing tests adequate, no new tests required
• All existing tests pass
• Untested

[mrice32]

LGTM!