Use default schemafactory in test.

Author: Claude

sdks/java/io/google-cloud-platform/src/test/java/org/apache/beam/sdk/io/gcp/bigquery/BigQueryTimestampPicosIT.java

@@ -441,7 +441,6 @@ public void testWriteGenericRecordTimestampNanos() throws Exception {
             "WriteGenericRecords",
             BigQueryIO.writeGenericRecords()
                 .to(tableSpec)
-                .withAvroSchemaFactory(tableSchema -> TIMESTAMP_NANOS_AVRO_SCHEMA)
                 .withSchema(BigQueryUtils.fromGenericAvroSchema(TIMESTAMP_NANOS_AVRO_SCHEMA, true))
                 .useAvroLogicalTypes()
                 .withMethod(BigQueryIO.Write.Method.STORAGE_WRITE_API)