CIP050 - Convert CLAM/USD+ to CLAM/USDC

Many in the DAO have decided that the yield from USD+ is not worth the risk given recent events.

We are earning about $14K a year in additional yield from being paired to USD+ in our LP, which would be a straight loss as we couldn't replace that yield outside of another yield-bearing stable. Because CLAM is paired with USD+, it's also a small upward pressure on CLAM demand because of the magic of LP mechanics.

Our Pentopia revenue would not be affected, as we could simply vote for CLAM/USDC.