fix(@angular-devkit/build-angular): clean translations when reloading

Currently when making a change while serving a localized application, duplicate
translation warnings appear for every translation id. This fixes that by replacing the whole translation object with a new one each time translations are loaded.

fixes #22398

packages/angular_devkit/build_angular/src/utils/i18n-options.ts

@@ -283,6 +283,7 @@ export function loadTranslations(
   logger: { warn: (message: string) => void; error: (message: string) => void },
   usedFormats?: Set<string>,
 ) {
+  let translations: Record<string, unknown>|undefined = undefined;
   for (const file of desc.files) {
     const loadResult = loader(path.join(workspaceRoot, file.path));
 
@@ -304,19 +305,20 @@ export function loadTranslations(
     file.format = loadResult.format;
     file.integrity = loadResult.integrity;
 
-    if (desc.translation) {
+    if (translations) {
       // Merge translations
       for (const [id, message] of Object.entries(loadResult.translations)) {
-        if (desc.translation[id] !== undefined) {
+        if (translations[id] !== undefined) {
           logger.warn(
             `WARNING [${file.path}]: Duplicate translations for message '${id}' when merging`,
           );
         }
-        desc.translation[id] = message;
+        translations[id] = message;
       }
     } else {
       // First or only translation file
-      desc.translation = loadResult.translations;
+      translations = loadResult.translations;
     }
   }
+  desc.translation = translations;
 }