Fix bug: artifact_registry_repository update always failing

[modular-magician]

This PR fixes a bug where trying to update a google_artifact_registry_repository always failed due to the fact that the resource's Update logic was hitting the wrong API endpoint.

You can reproduce the issue by applying the following configs in succession:

Original:

resource "google_artifact_registry_repository" "my-repo" {
  provider = google-beta

  location = "us-central1"
  repository_id = "my-repository"
  description = "example docker repository"
  format = "DOCKER"
}

New:

resource "google_artifact_registry_repository" "my-repo" {
  provider = google-beta

  location = "us-central1"
  repository_id = "my-repository"
  description = "example docker repository 2"
  format = "DOCKER"
}

Related bugs (with details on impact and priority):

• b/175713067
• Bug: ArtifactRegistryRepository errors with NotReady even after the registry has already been created. GoogleCloudPlatform/k8s-config-connector#348

If this PR is for Terraform, I acknowledge that I have:

• Searched through the issue tracker for an open issue that this either resolves or contributes to, commented on it to claim it, and written "fixes {url}" or "part of {url}" in this PR description. If there were no relevant open issues, I opened one and commented that I would like to work on it (not necessary for very small changes).
• Generated Terraform, and ran make test and make lint to ensure it passes unit and linter tests.
• Ensured that all new fields I added that can be set by a user appear in at least one example (for generated resources) or third_party test (for handwritten resources or update tests).
• Ran relevant acceptance tests (If the acceptance tests do not yet pass or you are unable to run them, please let your reviewer know).
• Read the Release Notes Guide before writing my release note below.

Release Note Template for Downstream PRs (will be copied)

artifactregistry: fixed issue where updating `google_artifact_registry_repository` always failed

Derived from GoogleCloudPlatform/magic-modules#4482