Ensure config preset schedule fork does not affect testnets #4780
Description
Describe the bug
Noticed that mainnet forks are scheduled in the mainnet config preset. All testnets extend that preset overwriting some properties. It is possible that a fork is scheduled for mainnet and not for some testnet, inadvertently causing that testnet to fork at a random epoch.
Expected behavior
Ensure that scheduled mainnet forks only affect the mainnet network