chore: migrate librarian to publish to new cloud-sdk-librarian-prod GCP project (#1805)

This additionally deprecates old AR exit gate cloud build file

Author: ldetmer

cloudbuild-exitgate-deprecated.yaml

@@ -0,0 +1,25 @@
+# Copyright 2025 Google LLC
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+# This Cloud Build configuration is used by a Louhi flow for the Artifact
+# Registry (AR) Exit Gate process (go/cloud-sdk-ar-exit-gate-onboarding).
+#
+# This build step creates the librarian container image and publishes it to the
+# 'images-dev' repository, which serves as the entry point for the AR Exit Gate.
+# After passing the gate's security checks, the image is promoted and
+# published to the 'images-prod' repository.
+steps:
+  - name: 'gcr.io/cloud-builders/docker'
+    args: ['build', '-t', 'us-central1-docker.pkg.dev/cloud-sdk-production-pipeline/images-dev/librarian', '.']
+images:
+  - 'us-central1-docker.pkg.dev/cloud-sdk-production-pipeline/images-dev/librarian'

cloudbuild-exitgate.yaml

@@ -20,6 +20,6 @@
 # published to the 'images-prod' repository.
 steps:
   - name: 'gcr.io/cloud-builders/docker'
-    args: ['build', '-t', 'us-central1-docker.pkg.dev/cloud-sdk-production-pipeline/images-dev/librarian', '.']
+    args: ['build', '-t', 'us-central1-docker.pkg.dev/cloud-sdk-librarian-prod/images-dev/librarian', '.']
 images:
-  - 'us-central1-docker.pkg.dev/cloud-sdk-production-pipeline/images-dev/librarian'
+  - 'us-central1-docker.pkg.dev/cloud-sdk-librarian-prod/images-dev/librarian'