externalTests: Neutralize npm hooks instead of replacing pragmas twice

- This also has the nice effect of stopping projects from trying to compile contracts during installation

test/externalTests/common.sh

@@ -104,6 +104,14 @@ function neutralize_package_lock
     rm --force --verbose package-lock.json
 }
 
+function neutralize_package_json_hooks
+{
+    printLog "Disabling package.json hooks..."
+    [[ -f package.json ]] || fail "package.json not found"
+    sed -i 's|"prepublish": *".*"|"prepublish": ""|g' package.json
+    sed -i 's|"prepare": *".*"|"prepare": ""|g' package.json
+}
+
 function force_truffle_solc_modules
 {
     local soljson="$1"