fix: contract verifier config test (#1583)

## What ❔

Makes contract verifier config test use the correct env var name

## Why ❔

Test is failing for me locally, no idea how it works on CI though

## Checklist

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core/lib/env_config/src/contract_verifier.rs

@@ -35,7 +35,7 @@ mod tests {
             CONTRACT_VERIFIER_PROMETHEUS_PORT=3314
             CONTRACT_VERIFIER_PORT=3070
             CONTRACT_VERIFIER_URL=127.0.0.1:3070
-            CONTRACT_THREADS_PER_SERVER=128
+            CONTRACT_VERIFIER_THREADS_PER_SERVER=128
 
         "#;
         lock.set_env(config);