build: remove express from externals list

The `@angular/ssr` package has no direct dependency on `express`, hence setting this as external is not required.

Author: alan-agius4

packages/angular/ssr/BUILD.bazel

@@ -37,7 +37,6 @@ ng_package(
     externals = [
         "@angular/ssr",
         "@angular/ssr/node",
-        "express",
         "../../third_party/critters",
     ],
     nested_packages = [