Enabled autocommit by default for pooled Oracle connections

The JDBC specification says that connections are expected to be in
autocommit mode by default. Oracle's UCP connection pool doesn't reset
the autocommit state when reusing an already created connection.
So we explicitly enable autocommit for any connection returned from the
pool to match the JDBC specification.

plugin/trino-oracle/src/main/java/io/trino/plugin/oracle/OraclePoolConnectionFactory.java

@@ -80,6 +80,10 @@ public OraclePoolConnectionFactory(
     public Connection openConnection(ConnectorSession session)
             throws SQLException
     {
-        return dataSource.getConnection();
+        Connection connection = dataSource.getConnection();
+        // Oracle's pool doesn't reset autocommit state of connections when reusing them so we explicitly enable
+        // autocommit by default to match the JDBC specification.
+        connection.setAutoCommit(true);
+        return connection;
     }
 }