Fix testDirectTrinoClientLongQuery

Example timings of processing pages in `DirectTrinoClient` during a local
run:
```
0.007584s
9.58E-4s
0.001542s
0.001792s
0.002708s
0.406709s
```

In this test, after processing each page, `DirectTrinoClient` waits 0.5s
and sends a heartbeat. The `query.client.timeout` is set to 1s.
Considering that processing the last page took 0.4s, it’s easy to
imagine that sometimes the total interval between sending heartbeats
exceeds 1s.

This test doesn’t care about the query output, so using `EXPLAIN ANALYZE`
and ignoring the results is fine. Now the example timings look as follows:
```
0.006958s
0.00125s
0.001292s
0.001875s
0.001333s
0.039125s
```

As an experiment, I reverted the bugfix that this test is validating,
and the test failed, so the intended behavior is still covered.

Author: piotrrzysko

testing/trino-tests/src/test/java/io/trino/client/direct/TestDirectTrinoClient.java

@@ -59,6 +59,6 @@ public void setup()
     @Timeout(value = 20, unit = TimeUnit.SECONDS)
     public void testDirectTrinoClientLongQuery()
     {
-        queryRunner.execute(TEST_SESSION, "SELECT * FROM blackhole.test_schema.slow_test_table");
+        queryRunner.execute(TEST_SESSION, "EXPLAIN ANALYZE SELECT * FROM blackhole.test_schema.slow_test_table");
     }
 }