refactor: move npm_registry_url to utils

[jbedard]

I'm not sure why I missed this, but it looks like this path is not tested on CI until merging to main? See https://github.com/aspect-build/rules_js/actions/runs/9248267733/job/25438315100

Changes are visible to end-users: no

Test plan

• Manual testing; please provide instructions so we can reproduce:

[aspect-workflows]

Test

All tests were cache hits

191 tests (100.0%) were fully cached saving 52s.

---

Test

e2e/bzlmod

All tests were cache hits

4 tests (100.0%) were fully cached saving 467ms.

---

Test

e2e/gyp_no_install_script

All tests were cache hits

2 tests (100.0%) were fully cached saving 693ms.

---

Test

e2e/js_image_oci

All tests were cache hits

1 test (100.0%) was fully cached saving 9s.

---

Test

e2e/npm_link_package

All tests were cache hits

2 tests (100.0%) were fully cached saving 1s.

---

Test

e2e/npm_link_package-esm

All tests were cache hits

2 tests (100.0%) were fully cached saving 923ms.

---

Test

e2e/npm_translate_lock

All tests were cache hits

1 test (100.0%) was fully cached saving 73ms.

---

Test

e2e/npm_translate_lock_empty

All tests were cache hits

1 test (100.0%) was fully cached saving 73ms.

---

Test

e2e/npm_translate_lock_multi

All tests were cache hits

2 tests (100.0%) were fully cached saving 271ms.

---

Test

e2e/npm_translate_lock_partial_clone

All tests were cache hits

1 test (100.0%) was fully cached saving 117ms.

---

Test

e2e/npm_translate_lock_subdir_patch

All tests were cache hits

1 test (100.0%) was fully cached saving 248ms.

---

Test

e2e/npm_translate_package_lock

All tests were cache hits

1 test (100.0%) was fully cached saving 73ms.

---

Test

e2e/npm_translate_yarn_lock

All tests were cache hits

1 test (100.0%) was fully cached saving 73ms.

---

Test

e2e/package_json_module

All tests were cache hits

1 test (100.0%) was fully cached saving 520ms.

---

Test

e2e/pnpm_lockfiles

All tests were cache hits

21 tests (100.0%) were fully cached saving 7s.

---

Test

e2e/pnpm_workspace

All tests were cache hits

8 tests (100.0%) were fully cached saving 3s.

---

Test

e2e/pnpm_workspace_rerooted

All tests were cache hits

6 tests (100.0%) were fully cached saving 2s.

---

Test

e2e/repo_mapping

All tests were cache hits

2 tests (100.0%) were fully cached saving 451ms.

---

Test

e2e/rules_foo

All tests were cache hits

2 tests (100.0%) were fully cached saving 605ms.

---

Test

e2e/vendored_node

All tests were cache hits

1 test (100.0%) was fully cached saving 187ms.

---

Buildifier      Format