Fix Rust 1.88 clippy errors & execution engine tests (#7657)

Fix Rust 1.88 clippy errors.

testing/execution_engine_integration/src/geth.rs

@@ -14,6 +14,10 @@ pub fn build_result(repo_dir: &Path) -> Output {
     Command::new("make")
         .arg("geth")
         .current_dir(repo_dir)
+        // Geth now uses the commit hash from a GitHub runner environment variable if it detects a CI environment.
+        // We need to override this to successfully build Geth in Lighthouse workflows.
+        // See: https://github.com/ethereum/go-ethereum/blob/668c3a7278af399c0e776e92f1c721b5158388f2/internal/build/env.go#L95-L121
+        .env("CI", "false")
         .output()
         .expect("failed to make geth")
 }