docs: update iam policy sample user to be consistent with other languages (#3429)

* docs: update iam policy sample user to be consistent with other language samples

* fix format

* 🦉 Updates from OwlBot post-processor

See https://github.com/googleapis/repo-automation-bots/blob/main/packages/owl-bot/README.md

---------

Co-authored-by: Owl Bot <gcf-owl-bot[bot]@users.noreply.github.com>

Author: PhongChuong

README.md

@@ -53,7 +53,7 @@ If you are using Maven without the BOM, add this to your dependencies:
 If you are using Gradle 5.x or later, add this to your dependencies:
 
 ```Groovy
-implementation platform('com.google.cloud:libraries-bom:26.43.0')
+implementation platform('com.google.cloud:libraries-bom:26.44.0')
 
 implementation 'com.google.cloud:google-cloud-bigquery'
 ```

samples/snippets/src/main/java/com/example/bigquery/CreateIamPolicy.java

@@ -46,7 +46,9 @@ public static void createIamPolicy(String datasetName, String tableName) {
       Policy policy = bigquery.getIamPolicy(tableId);
       policy
           .toBuilder()
-          .addIdentity(Role.of("roles/bigquery.dataViewer"), Identity.allUsers())
+          .addIdentity(
+              Role.of("roles/bigquery.dataViewer"),
+              Identity.user("example-analyst-group@google.com"))
           .build();
       bigquery.setIamPolicy(tableId, policy);
       System.out.println("Iam policy created successfully");