fix: add missing globals from each rollup configuration (#20028)

PR Close #20028

packages/http/rollup.config.js

@@ -14,6 +14,7 @@ const globals = {
   '@angular/compiler': 'ng.compiler',
   '@angular/platform-browser': 'ng.platformBrowser',
   'rxjs/Observable': 'Rx',
+  'rxjs/Observer': 'Rx',
   'rxjs/Subject': 'Rx'
 };