fix(rspack): fix issue where optimization options are removed from rspack config (nrwl#31268)

Author: konqi

packages/rspack/src/plugins/utils/apply-base-config.ts

@@ -147,10 +147,10 @@ function applyNxIndependentConfig(
     ...(config.ignoreWarnings ?? []),
   ];
 
-  config.optimization = !isProd
-    ? undefined
-    : {
+  config.optimization = 
+  {
         ...(config.optimization ?? {}),
+        ...(isProd ? {
         sideEffects: true,
         minimize:
           typeof options.optimization === 'object'
@@ -182,7 +182,7 @@ function applyNxIndependentConfig(
         runtimeChunk: isDevServer
           ? config.optimization?.runtimeChunk ?? undefined
           : false,
-      };
+      } : {})};
 
   config.stats = {
     hash: true,