sample: remove AwsCrossAccountRole from AWS sample. (#850)

fix: remove AwsCrossAccountRole from AWS sample.

This was updated in https://togithub.com/googleapis/java-bigqueryconnection/pull/576/files, but one reference to AwsCrossAccountRole was not changed, which causes the sample to not work as the cross account role is no longer supported.

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Fixes #<issue_number_goes_here> ☕️

If you write sample code, please follow the [samples format](
https://togithub.com/GoogleCloudPlatform/java-docs-samples/blob/main/SAMPLE_FORMAT.md).

README.md

@@ -34,13 +34,13 @@ If you are using Maven, add this to your pom.xml file:
 If you are using Gradle without BOM, add this to your dependencies:
 
 ```Groovy
-implementation 'com.google.cloud:google-cloud-bigqueryconnection:2.19.0'
+implementation 'com.google.cloud:google-cloud-bigqueryconnection:2.20.0'
 ```
 
 If you are using SBT, add this to your dependencies:
 
 ```Scala
-libraryDependencies += "com.google.cloud" % "google-cloud-bigqueryconnection" % "2.19.0"
+libraryDependencies += "com.google.cloud" % "google-cloud-bigqueryconnection" % "2.20.0"
 ```
 
 ## Authentication

samples/snippets/src/main/java/com/example/bigqueryconnection/CreateAwsConnection.java

@@ -18,7 +18,6 @@
 
 // [START bigqueryconnection_create_aws_connection]
 import com.google.cloud.bigquery.connection.v1.AwsAccessRole;
-import com.google.cloud.bigquery.connection.v1.AwsCrossAccountRole;
 import com.google.cloud.bigquery.connection.v1.AwsProperties;
 import com.google.cloud.bigquery.connection.v1.Connection;
 import com.google.cloud.bigquery.connection.v1.CreateConnectionRequest;
@@ -37,8 +36,8 @@ public static void main(String[] args) throws IOException {
     String connectionId = "MY_CONNECTION_ID";
     // Example of role id: arn:aws:iam::accountId:role/myrole
     String iamRoleId = "MY_AWS_ROLE_ID";
-    AwsCrossAccountRole role = AwsCrossAccountRole.newBuilder().setIamRoleId(iamRoleId).build();
-    AwsProperties awsProperties = AwsProperties.newBuilder().setCrossAccountRole(role).build();
+    AwsAccessRole role = AwsAccessRole.newBuilder().setIamRoleId(iamRoleId).build();
+    AwsProperties awsProperties = AwsProperties.newBuilder().setAccessRole(role).build();
     Connection connection = Connection.newBuilder().setAws(awsProperties).build();
     createAwsConnection(projectId, location, connectionId, connection);
   }