fix(@angular/build): address review feedback in persistent load result cache

Uniformly deduplicate watch files via a single Set to avoid redundant stat and readFile operations during metadata computation when result.watchFiles contains duplicates.

Author: alan-agius4

packages/angular/build/src/tools/esbuild/persistent-load-result-cache.ts

@@ -316,9 +316,9 @@ export class PersistentLoadResultCache implements LoadResultCache {
       const knownContents = filePath
         ? new Map<string, string | Uint8Array>([[filePath, content]])
         : undefined;
-      const allWatchFiles = filePath
-        ? Array.from(new Set([filePath, ...(result.watchFiles ?? [])]))
-        : (result.watchFiles ?? []);
+      const allWatchFiles = Array.from(
+        new Set(filePath ? [filePath, ...(result.watchFiles ?? [])] : result.watchFiles),
+      );
       const watchFilesMetadata = await computeMetadataForWatchFiles(allWatchFiles, knownContents);
 
       await this.persistentStore.put(cacheKey, {