Adjust USDT and USDC lending market params (within jump rate 50% limit)

Interlay referendum 96 was passed to adjust USDT and USDC lending market params. However, it failed to execute because the Interlay runtime has a hard-coded maximum “full rate” of 50% and the referendum aimed to set it to 150%. I have proposed a GitHub Pull Request to fix this issue. However, while the Interlay team is focused on launching BOB we won’t get a runtime upgrade for a bit. Therefore, this referendum implements most of the original proposed changes sans the “full rate” being increased.

This proposal will:

• increases USDT supply cap $600k -> $2M
• increases USDT and USDC jump rate to 20% to incentivize people to loan more collateral on the Interlay platform.
• increases USDT liquidation threshold from 74% to 87%. The USDC market was recently opened with a higher 87% liquidation threshold. Since token volatility is low, the “collateralization analysis” tool indicated a much higher threshold but we’ll simply increase to 87% to be conservative and match USDC.

This proposal will NOT:

• increase the "full rate" from 50% to 150% to encourage paying back loans and restore liquidity to the lending market. That change can't be made until there's a runtime upgrade.
• until we increase the "full rate" I also left the optimal utilization at 90% instead of lowering to 80%. Leaving it at 90% for now maximizes protocol revenue. (and not lull borrowers into a false sense of security that the APR curve above the optimal point is very flat)

Additionally, this proposal makes two transfers:

• retry tipping jose.crypto $1000 (nominated by CAP) for his Interlay community support
• reimburse me the original 13 hours and an additional 8 hours investigating why referenda 96 failed to execute, learned to use Chopsticks UI to debug, and created a pull request to widen the MAX limits for jump model "full rate" to avoid this failure in the future. (21hrs x $100/hr = $2,100)