test: raise timeout of //packages/ngtools/webpack:test

This seems to be timing out occasionally in CI.

(cherry picked from commit d96a093)

Author: dgp1130

packages/ngtools/webpack/BUILD.bazel

@@ -57,6 +57,7 @@ ts_project(
 
 jasmine_test(
     name = "test",
+    size = "medium",
     data = [
         ":webpack_test_lib",
         # Needed at runtime for runtime TS compilations performed by tests.