[ci]: update flake detection to only run in Turbopack (#84659)

Flake detection runs changed test(s) 6 times: 3 in Webpack, 3 in
Turbopack. for the purposes of detecting flakes, and to reduce the
burden on CI, this runs flake detection only with Turbopack (esp. now
that it's enabled by default).

Author: ztanner

scripts/test-new-tests.mjs

@@ -128,34 +128,19 @@ async function main() {
     }
   }
 
-  for (let i = 0; i < attempts; i++) {
-    console.log(`\n\nRun ${i + 1}/${attempts} for ${testMode} tests (Webpack)`)
-
-    // We apply the external tests filter before the process.env so that if
-    // it's defined in the environment, it overrides the default filter.
-    // This is required for supporting the experimental tests setup.
-    const NEXT_EXTERNAL_TESTS_FILTERS = process.env.NEXT_EXTERNAL_TESTS_FILTERS
-      ? process.env.NEXT_EXTERNAL_TESTS_FILTERS
-      : testMode === 'deploy'
-        ? 'test/deploy-tests-manifest.json'
-        : undefined
-
-    if (NEXT_EXTERNAL_TESTS_FILTERS) {
-      console.log(
-        `Applying external tests filter: ${NEXT_EXTERNAL_TESTS_FILTERS}`
-      )
-    }
+  // We apply the external tests filter before the process.env so that if
+  // it's defined in the environment, it overrides the default filter.
+  // This is required for supporting the experimental tests setup.
+  const NEXT_EXTERNAL_TESTS_FILTERS = process.env.NEXT_EXTERNAL_TESTS_FILTERS
+    ? process.env.NEXT_EXTERNAL_TESTS_FILTERS
+    : testMode === 'deploy'
+      ? 'test/deploy-tests-manifest.json'
+      : undefined
 
-    await execa('node', [...RUN_TESTS_ARGS, ...currentTests], {
-      ...EXECA_OPTS_STDIO,
-      env: {
-        ...process.env,
-        NEXT_EXTERNAL_TESTS_FILTERS,
-        NEXT_TEST_MODE: testMode,
-        NEXT_TEST_VERSION: nextTestVersion,
-        IS_WEBPACK_TEST: '1',
-      },
-    })
+  if (NEXT_EXTERNAL_TESTS_FILTERS) {
+    console.log(
+      `Applying external tests filter: ${NEXT_EXTERNAL_TESTS_FILTERS}`
+    )
   }
 
   if (isFlakeDetectionMode && testMode !== 'deploy') {
@@ -175,6 +160,21 @@ async function main() {
         },
       })
     }
+  } else {
+    for (let i = 0; i < attempts; i++) {
+      console.log(`\n\nRun ${i + 1}/${attempts} for ${testMode} tests`)
+
+      await execa('node', [...RUN_TESTS_ARGS, ...currentTests], {
+        ...EXECA_OPTS_STDIO,
+        env: {
+          ...process.env,
+          NEXT_EXTERNAL_TESTS_FILTERS,
+          NEXT_TEST_MODE: testMode,
+          NEXT_TEST_VERSION: nextTestVersion,
+          IS_WEBPACK_TEST: '1',
+        },
+      })
+    }
   }
 }