ci: Use versions.json consistently in Circle CI config

[sebastianst]

In #9117, installation of a new tool eth2-testnet-genesis was added to the Circle CI config. It references the version from the versions.json file. However, other software that is installed in CI still hardcodes the version, leading to inconsistent use of versions, for example (incomplete list)

• nvm version
• node version (the keyword nvm is used in versions.json to set the node version, this should also be improved)
• geth
• foundry

The version can be accessed like $(jq -r .eth2_testnet_genesis < versions.json), see also b9216e2.

Ideally we specify as many versions as possible in the versions.json file and then consistently use them across different contexts, e.g. in CI as well as the ci-builder.

Note that it may be necessary to specify additional versions in the versions file, and possibly also some checksums for some software, like geth.