Generate valid states and blocks for CI testing

**Describe the bug**

Current master depends on Infura to download some states and blocks for benchmarking. While this has worked fine before currently Infura timeouts for all requests. The problem is that these states are really old and Infura places some limit on the credentials. I've rotated the credentials with a new account but it still timeouts.

Depending on external services weakens our CI. This issue is blocking https://github.com/ChainSafe/lodestar/pull/3995

**Proposed solution**

Build generic infra to generate valid states and blocks on demand and cache them locally. We already have something like that for benchmarking but should be extended and persisted.