Integration tests ergonomics (#7836)

Fixes #7785


  - [x] Update all integration tests with >1 files to follow the `main` pattern.
- [x] `crypto/eth2_key_derivation/tests`
- [x] `crypto/eth2_keystore/tests`
- [x] `crypto/eth2_wallet/tests`
- [x] `slasher/tests`
- [x] `common/eth2_interop_keypairs/tests`
- [x] `beacon_node/lighthouse_network/tests`
- [x] Set `debug_assertions` to false on `.vscode/settings.json`.
- [x] Document how to make rust analyzer work on integration tests files. In `book/src/contributing_setup.md`

---

Tracking a `rust-analyzer.toml` with settings like the one provided in `.vscode/settings.json` would be nicer. But this is not possible yet. For now, that config should be a good enough indicator for devs using editors different to VSCode.


Co-Authored-By: Daniel Ramirez-Chiquillo <hi@danielrachi.com>

Co-Authored-By: Michael Sproul <michael@sigmaprime.io>

crypto/eth2_key_derivation/Cargo.toml

@@ -3,6 +3,7 @@ name = "eth2_key_derivation"
 version = "0.1.0"
 authors = ["Paul Hauner <paul@paulhauner.com>"]
 edition = { workspace = true }
+autotests = false
 # See more keys and their definitions at https://doc.rust-lang.org/cargo/reference/manifest.html
 
 [dependencies]
@@ -14,3 +15,7 @@ zeroize = { workspace = true }
 
 [dev-dependencies]
 hex = { workspace = true }
+
+[[test]]
+name = "eth2_key_derivation_tests"
+path = "tests/main.rs"