test: make tmpdir.js importable from esm

PR-URL: #44322
Reviewed-By: Rich Trott <[email protected]>
Reviewed-By: Moshe Atlow <[email protected]>
Reviewed-By: Antoine du Hamel <[email protected]>
Reviewed-By: Tobias Nießen <[email protected]>
Reviewed-By: Ian Sutherland <[email protected]>
Reviewed-By: Luigi Pinca <[email protected]>

Author: GeoffreyBooth

test/common/tmpdir.js

@@ -19,8 +19,8 @@ const tmpPath = path.join(testRoot, tmpdirName);
 
 let firstRefresh = true;
 function refresh() {
-  rmSync(this.path);
-  fs.mkdirSync(this.path);
+  rmSync(tmpPath);
+  fs.mkdirSync(tmpPath);
 
   if (firstRefresh) {
     firstRefresh = false;