test: update rebuild debounce times to reduce flakiness

Author: clydin

packages/angular_devkit/build_angular/src/browser/specs/unused-files-warning_spec.ts

@@ -178,7 +178,8 @@ describe('Browser Builder unused files warnings', () => {
 
     await run.output
       .pipe(
-        debounceTime(1000),
+        // Same time as the rebuild specs
+        debounceTime(3000),
         tap(buildEvent => {
           expect(buildEvent.success).toBe(true);
 

packages/angular_devkit/build_angular/src/browser/specs/web-worker_spec.ts

@@ -147,7 +147,8 @@ describe('Browser Builder Web Worker support', () => {
     const { run } = await timer(1000).pipe(
       switchMap(() => architect.scheduleTarget(target, overrides)),
       switchMap(run => run.output.pipe(map(output => ({ run, output })))),
-      debounceTime(500),
+      // Same time as the rebuild specs
+      debounceTime(3000),
       tap(({ output }) => expect(output.success).toBe(true, 'build should succeed')),
       tap(() => {
         switch (phase) {