fix(@angular-devkit/build-angular): correctly set ngDevMode in esbuilder

During development we should not set `ngDevMode` to `true`, as this is expected to be an object literal.

Closes #23627

(cherry picked from commit aa83feb)

Author: alan-agius4

packages/angular_devkit/build_angular/src/builders/browser-esbuild/index.ts

@@ -346,7 +346,7 @@ async function bundleCode(
       ),
     ],
     define: {
-      'ngDevMode': optimizationOptions.scripts ? 'false' : 'true',
+      ...(optimizationOptions.scripts ? { 'ngDevMode': 'false' } : undefined),
       'ngJitMode': 'false',
     },
   });