fix: replace Coinbase delisted EUROC pairs

[nvtaveras]

Description

This replaces the delisted EUROCUSD pair on Coinbase with an implicit pairs that goes through EUROCUSDC instead.

Tested

Not yet tested. I’ll recommend doing the following for both EUROC/EUR and EUROC/XOF (as they were both updated):

1. Run the price source configuration locally. I’d recommend doing two runs:
   1. First run using an existing price source that it’s currently working and doesn’t involve Coinbase’s EUROC/USD. Take note of the price reported
   2. A second run using only the price source configuration that involves the new Coinbase EUROC/USDC pair. The price reported should be very close to the previous run.
   3. A final run using all the price sources configuration from the helm charts in the PR.

Related issues

• Fixes https://github.com/mento-protocol/mento-general/issues/612