[java-spanner-jdbc] Spanner: Unknown type: INTERVAL when reading from ResultSet

#### Environment details

2. OS type and version: Microsoft Windows [Version 10.0.26100.7171]
3. Java version: openjdk version "21.0.7" 2025-04-15 LTS
4. version(s): I'm working with the spanner emulator: https://github.com/GoogleCloudPlatform/cloud-spanner-emulator and JDBC driver version: `com.google.cloud:google-cloud-spanner-jdbc:2.34.0`

#### Code example

```java
ResultSet rs = connection.createStatement().executeQuery("select interval 1 day");
rs.next();
println(rs.getObject(1).getClass());
```

The same happens when reading the type with `ResultSet::getString`. Internally, a string value is available, and it is in an expected format, so I would assume that at least the string value should be accessible:

#### Stack trace
```
com.google.cloud.spanner.jdbc.JdbcSqlExceptionFactory$JdbcSqlExceptionImpl: INVALID_ARGUMENT: Unknown type: INTERVAL
at com.google.cloud.spanner.jdbc.JdbcSqlExceptionFactory.of(JdbcSqlExceptionFactory.java:247)
at com.google.cloud.spanner.jdbc.JdbcResultSet.getObject(JdbcResultSet.java:837)
at com.google.cloud.spanner.jdbc.JdbcResultSet.getObject(JdbcResultSet.java:796)
at org.jooq.testscripts.JDBC.main(JDBC.java:42)
```