Only enable mixedModules for edge config test

test/integration.test.js

@@ -13,6 +13,7 @@ const integrationDir = `${__dirname}${path.sep}integration`;
 for (const integrationTest of readdirSync(integrationDir)) {
   it(`should correctly trace and correctly execute ${integrationTest}`, async () => {
     console.log('Tracing and executing ' + integrationTest);
+    const mixedModules = integrationTest === 'vercel-edge-config-esm.mjs';
     const nftCache = {}
     const fails = integrationTest.endsWith('failure.js');
     const { fileList, reasons, warnings } = await nodeFileTrace([`${integrationDir}/${integrationTest}`], {
@@ -22,7 +23,7 @@ for (const integrationTest of readdirSync(integrationDir)) {
       processCwd: integrationDir,
       // ignore other integration tests
       ignore: ['test/integration/**'],
-      mixedModules: true
+      mixedModules
     });
     // warnings.forEach(warning => console.warn(warning));
     const randomTmpId = Math.random().toString().slice(2)
@@ -64,7 +65,7 @@ for (const integrationTest of readdirSync(integrationDir)) {
         processCwd: integrationDir,
         // ignore other integration tests
         ignore: ['test/integration/**'],
-        mixedModules: true
+        mixedModules
       });
       expect([...cachedResult.fileList].sort()).toEqual([...fileList].sort())
     }