Fulfill prop #11784 by disabling USTC minting via raising Tobin tax to 100%

*This is a proposal solely to fulfill prop #11784 - "STOP MINTING AND REMINTING OF USTC"* The only minting of USTC currently happening on chain is through the market module, which allows burning a coin to mint another. This mechanism was disabled for LUNC<->Stable by raising the spread to 100% during the crash, effectively disabling swapping from and to LUNC through the market module. For swapping Stable<->Stable instead of the spread a Tobin tax is used. Setting the Tobin tax to 100% effectively disables swapping the corresponding asset. To fulfill proposal 11784, Vinh from the L1TF already implemented a code change to introduce a new governance parameter that specifically allows setting a Tobin tax for swaps to USTC (the only action that mints USTC). As there is no real exit-route from stables other than USTC anyway, it was discussed to simply raise all Tobin taxes for all stables to 100% instead of a code change. This has the side-effect of disabling market swaps between all stables instead of just swaps *to* USTC. This proposal aims to do as mentioned and raise the Tobin for all stables to 100%, effectively disabling all market swapping and such minting of coins on Terra Classic. Potential pros: No code change / software upgrade needed, USTC minting disabled Potential cons: Swapping between stables (e.g. USTC->EUTC) is also disabled, USTC burning through swaps disabled Important: This does only affect the market swap. It does not affect swapping coins through DEXes like Terraswap. This continues to be possible for existing pairs. If this proposal fails to pass, the route of a software change should be followed to specifically disable swapping TO USTC without touching other stable swaps. Swapping any stable assets to USTC would be disabled with every other solution anyway, as there is no way to prevent minting USTC without disabling the swap to it. What your vote means: Yes: Raise Tobin tax to 100% for all stables on Terra Classic No: Fall back to the prepared code-change solution Abstain: Do what the majority decides No with veto: - Disclaimer: The idea of choosing the "simple route" using Tobin tax to disable swaps originates from a discord chat around how to fulfill passed proposal 11784. This solution exceeds the scope of the original proposal which didn't mention any other assets than USTC. When voting you should be aware and discuss about the potential pros and cons of this solution. There was a test conducted on rebel-2 testnet to ensure that this solution does not result in a loss of funds when someone would try to make a swap with 100% Tobin tax. The chain returned an error about zero swap coins during these tests, so the tx failed and no funds were consumed.