Specify a localRepositoryPath for integration tests.

The upgrade to version 3.5.0 of `maven-invoker-plugin` caused this project to fail, with the message here:
```
Failed to execute goal org.apache.maven.plugins:maven-invoker-plugin:3.5.0:install (integration-test) on project auto-value: Failed to install artifact com.google.auto:auto-common:jar:1.2.1: cannot install /home/runner/.m2/repository/com/google/auto/auto-common/1.2.1/auto-common-1.2.1.jar to same path -> [Help 1]
```

Setting `localRepositoryPath` fixes this.

I believe the change in behaviour was caused by [this PR](apache/maven-invoker-plugin#174), which may have broken other projects similarly. But it has always been [recommended](https://maven.apache.org/plugins/maven-invoker-plugin/integration-test-mojo.html#localRepositoryPath) to use a non-default `localRepositoryPath` anyway.

RELNOTES=n/a
PiperOrigin-RevId: 510177767

factory/pom.xml

@@ -199,6 +199,7 @@
         <configuration>
           <addTestClassPath>true</addTestClassPath>
           <cloneProjectsTo>${project.build.directory}/it</cloneProjectsTo>
+          <localRepositoryPath>${project.build.directory}/it-repo</localRepositoryPath>
           <pomIncludes>
             <pomInclude>*/pom.xml</pomInclude>
           </pomIncludes>

value/pom.xml

@@ -183,6 +183,7 @@
           <configuration>
             <addTestClassPath>true</addTestClassPath>
             <cloneProjectsTo>${project.build.directory}/it</cloneProjectsTo>
+            <localRepositoryPath>${project.build.directory}/it-repo</localRepositoryPath>
             <pomIncludes>
               <pomInclude>*/pom.xml</pomInclude>
             </pomIncludes>