[ddc] Use prebuilt_dart_action to build js

Start using the prebuilt_dart_action again to run ddc when compiling
packages to js.

This reverts the change made in
https://dart-review.googlesource.com/c/sdk/+/151400
that was needed when adding packages to the null safety allow list.

Change-Id: I291f127729c38c6bc22e3b74f87c38b9f11661c4
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/155547
Reviewed-by: Jake Macdonald <jakemac@google.com>
Commit-Queue: Nicholas Shahan <nshahan@google.com>

Author: nshahan

utils/dartdevc/BUILD.gn

@@ -204,7 +204,7 @@ template("dartdevc_kernel_compile") {
   #     named `${name}_js` must exist.
   #   * args: additional args to pass to dartdevc
 
-  dart_action(target_name) {
+  prebuilt_dart_action(target_name) {
     script = "../../pkg/dev_compiler/bin/dartdevc.dart"
     module = invoker.package
     out_dir = rebase_path("$js_gen_dir")