ci: Add .kokoro/settings.xml to use maven mirror (#1255)

.kokoro/presubmit/downstream-build.sh

@@ -27,7 +27,7 @@ fi
 
 # Use GCP Maven Mirror
 mkdir -p "${HOME}/.m2"
-cp settings.xml "${HOME}/.m2"
+cp .kokoro/settings.xml "${HOME}/.m2"
 
 ### Round 1
 # Publish this repo's modules to local maven to make them available for downstream libraries

.kokoro/settings.xml

@@ -0,0 +1,32 @@
+<!--
+  ~ Copyright 2022 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.
+  -->
+
+<settings xmlns="http://maven.apache.org/SETTINGS/1.0.0"
+  xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
+  xsi:schemaLocation="http://maven.apache.org/SETTINGS/1.0.0
+                          https://maven.apache.org/xsd/settings-1.0.0.xsd">
+  <mirrors>
+    <mirror>
+      <!-- Google's Maven Central mirror for Americas
+       https://maven-central.storage.googleapis.com/index.html
+      -->
+      <id>google-maven-central</id>
+      <name>GCS Maven Central mirror</name>
+      <url>https://maven-central.storage-download.googleapis.com/maven2/</url>
+      <mirrorOf>central</mirrorOf>
+    </mirror>
+  </mirrors>
+</settings>