refactor(turbopack): Disable tree shaking by default (#73421)

### What?

Disable tree shaking by default

### Why?

x-ref: https://vercel.slack.com/archives/C03EWR7LGEN/p1733106700499869

### How?

Author: kdy1

crates/next-core/src/next_config.rs

@@ -1246,7 +1246,7 @@ impl NextConfig {
     #[turbo_tasks::function]
     pub fn tree_shaking_mode_for_foreign_code(
         &self,
-        is_development: bool,
+        _is_development: bool,
     ) -> Vc<OptionTreeShaking> {
         let tree_shaking = self
             .experimental
@@ -1257,19 +1257,13 @@ impl NextConfig {
         OptionTreeShaking(match tree_shaking {
             Some(false) => Some(TreeShakingMode::ReexportsOnly),
             Some(true) => Some(TreeShakingMode::ModuleFragments),
-            None => {
-                if is_development {
-                    Some(TreeShakingMode::ReexportsOnly)
-                } else {
-                    Some(TreeShakingMode::ModuleFragments)
-                }
-            }
+            None => Some(TreeShakingMode::ReexportsOnly),
         })
         .cell()
     }
 
     #[turbo_tasks::function]
-    pub fn tree_shaking_mode_for_user_code(&self, is_development: bool) -> Vc<OptionTreeShaking> {
+    pub fn tree_shaking_mode_for_user_code(&self, _is_development: bool) -> Vc<OptionTreeShaking> {
         let tree_shaking = self
             .experimental
             .turbo
@@ -1279,13 +1273,7 @@ impl NextConfig {
         OptionTreeShaking(match tree_shaking {
             Some(false) => Some(TreeShakingMode::ReexportsOnly),
             Some(true) => Some(TreeShakingMode::ModuleFragments),
-            None => {
-                if is_development {
-                    Some(TreeShakingMode::ReexportsOnly)
-                } else {
-                    Some(TreeShakingMode::ModuleFragments)
-                }
-            }
+            None => Some(TreeShakingMode::ReexportsOnly),
         })
         .cell()
     }

test/turbopack-build-tests-manifest.json

@@ -15604,68 +15604,68 @@
       "runtimeError": false
     },
     "test/production/app-dir/actions-tree-shaking/basic/basic.test.ts": {
-      "passed": [
+      "passed": [],
+      "failed": [
         "actions-tree-shaking - basic should not have the unused action in the manifest"
       ],
-      "failed": [],
       "pending": [],
       "flakey": [],
       "runtimeError": false
     },
     "test/production/app-dir/actions-tree-shaking/mixed-module-actions/mixed-module-actions-edge.test.ts": {
-      "passed": [
+      "passed": [],
+      "failed": [
         "actions-tree-shaking - mixed-module-actions should not do tree shake for cjs module when import server actions"
       ],
-      "failed": [],
       "pending": [],
       "flakey": [],
       "runtimeError": false
     },
     "test/production/app-dir/actions-tree-shaking/mixed-module-actions/mixed-module-actions.test.ts": {
-      "passed": [
+      "passed": [],
+      "failed": [
         "actions-tree-shaking - mixed-module-actions should not do tree shake for cjs module when import server actions"
       ],
-      "failed": [],
       "pending": [],
       "flakey": [],
       "runtimeError": false
     },
     "test/production/app-dir/actions-tree-shaking/reexport/reexport-edge.test.ts": {
-      "passed": [
-        "actions-tree-shaking - reexport should not have the unused action in the manifest"
-      ],
+      "passed": [],
       "failed": [
+        "actions-tree-shaking - reexport should not tree-shake namespace exports the manifest",
+        "actions-tree-shaking - reexport should not have the unused action in the manifest",
         "actions-tree-shaking - reexport should keep all the action exports for namespace export case on client layer"
       ],
       "pending": [],
       "flakey": [],
       "runtimeError": false
     },
     "test/production/app-dir/actions-tree-shaking/reexport/reexport.test.ts": {
-      "passed": [
-        "actions-tree-shaking - reexport should not have the unused action in the manifest"
-      ],
+      "passed": [],
       "failed": [
+        "actions-tree-shaking - reexport should not tree-shake namespace exports the manifest",
+        "actions-tree-shaking - reexport should not have the unused action in the manifest",
         "actions-tree-shaking - reexport should keep all the action exports for namespace export case on client layer"
       ],
       "pending": [],
       "flakey": [],
       "runtimeError": false
     },
     "test/production/app-dir/actions-tree-shaking/shared-module-actions/shared-module-actions-edge.test.ts": {
-      "passed": [
+      "passed": [],
+      "failed": [
         "actions-tree-shaking - shared-module-actions should not have the unused action in the manifest"
       ],
-      "failed": [],
       "pending": [],
       "flakey": [],
       "runtimeError": false
     },
     "test/production/app-dir/actions-tree-shaking/shared-module-actions/shared-module-actions.test.ts": {
-      "passed": [
+      "passed": [],
+      "failed": [
         "actions-tree-shaking - shared-module-actions should not have the unused action in the manifest"
       ],
-      "failed": [],
       "pending": [],
       "flakey": [],
       "runtimeError": false
@@ -15689,10 +15689,10 @@
       "runtimeError": false
     },
     "test/production/app-dir/actions-tree-shaking/client-actions-tree-shaking/client-actions-tree-shaking.test.ts": {
-      "passed": [
+      "passed": [],
+      "failed": [
         "app-dir - client-actions-tree-shaking should not bundle unused server reference id in client bundles"
       ],
-      "failed": [],
       "pending": [],
       "flakey": [],
       "runtimeError": false