[EPIC] Switch to USDC

[trizin]

Code Changes

• [x] https://github.com/oceanprotocol/pdr-backend/issues/1750
• [ ] #1756
• [x] #1755
• [x] #1752
• [ ] Set prediction token address to USDC in web3_pp
• [ ] Check and clean up remaining OCEAN instances in
• [ ] Prepare a guide on how to migrate old clients

Note: Updated related README files in each step

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[!WARNING]
NEXT STEPS WILL BREAK OLD CLIENTS

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Deployment

First do on Testnet, then on Mainnet:

• Ensure all tests green.
• Calculate and set the weekly target consumption rate in USDC for dfbuyer
• Call pausePredictions on existing contracts to stop predictions.
• Deploy 10 new pairs on the network (with web3_pp.prediction_token set to USDC)
• Deploy updated pdr-backend components to our Kubernetes cluster
  • Deploy trueval
  • Deploy dfbuyer
• Test all pdr-backend components are working.
• Test frontend.