ensure zkSync checkout works with v2

**User Story:**

This ticket has 2 goals :

#### Disabling zksync checkout during merge
**For Product @lthrift**
Currently, we have a toggle switch that would have to be set to true and the zkync option gets grey-ed out with a message saying this service is not available
We just have to update this : https://gitcoin.co/_administrationperftools/staticjsonenv/5/change/

Once product tests this out on staging, a follow up ticket with messaging can be made

#### Migrating to zksync v2

This would involve exploring and migrating our zksync integration to v2 so that we can avoid downtime of any kind.
More context on how to go about this is documented here: https://github.com/gitcoinco/web/issues/10825#issuecomment-1246252968

Even if we do the v2 migration -> me and @kevinrolsen recommend :
- sticking with the old version of zksync and using the disable flag
- roll out the v2 once the round ends -> (less surface area for errors -> impacts lesser customers)

**Notes/Assumptions:**
From Matter Labs:
Ciao guys, we wanted to give you an advance notice that around the time of the Merge, we will be suspending L2 operations for zkSync V1. This is to minimize any potential risks. A full communication with more details will follow but we wanted to give you a heads up.
https://twitter.com/zksync/status/1567133179764686848?s=20&t=2eHURVxx7miOqPYqluB15A