Fix flaky TestQueryManagerConfig

This test relies on rounding large integers and will sometimes fail
depending on the amount of memory available to the test runner.

This commit reuses the exact same calculation for tests as it does in
the code, so that we will always get the correct value for the default.

core/trino-main/src/test/java/io/trino/execution/TestQueryManagerConfig.java

@@ -28,6 +28,7 @@
 import static io.airlift.units.DataSize.Unit.KILOBYTE;
 import static io.airlift.units.DataSize.Unit.MEGABYTE;
 import static io.trino.execution.QueryManagerConfig.AVAILABLE_HEAP_MEMORY;
+import static io.trino.execution.QueryManagerConfig.DEFAULT_TASK_DESCRIPTOR_STORAGE_MAX_MEMORY;
 import static io.trino.execution.QueryManagerConfig.FAULT_TOLERANT_EXECUTION_MAX_PARTITION_COUNT_LIMIT;
 import static java.lang.Math.max;
 import static java.lang.Math.round;
@@ -100,8 +101,8 @@ public void testDefaults()
                 .setFaultTolerantExecutionStandardSplitSize(DataSize.of(64, MEGABYTE))
                 .setFaultTolerantExecutionMaxTaskSplitCount(2048)
                 .setFaultTolerantExecutionTaskDescriptorStorageMaxMemory(DataSize.ofBytes(round(AVAILABLE_HEAP_MEMORY * 0.15)))
-                .setFaultTolerantExecutionTaskDescriptorStorageHighWaterMark(DataSize.ofBytes((long) (AVAILABLE_HEAP_MEMORY * 0.09)))
-                .setFaultTolerantExecutionTaskDescriptorStorageLowWaterMark(DataSize.ofBytes((long) (AVAILABLE_HEAP_MEMORY * 0.06)))
+                .setFaultTolerantExecutionTaskDescriptorStorageHighWaterMark(DataSize.ofBytes((long) (DEFAULT_TASK_DESCRIPTOR_STORAGE_MAX_MEMORY.toBytes() * 0.6)))
+                .setFaultTolerantExecutionTaskDescriptorStorageLowWaterMark(DataSize.ofBytes((long) (DEFAULT_TASK_DESCRIPTOR_STORAGE_MAX_MEMORY.toBytes() * 0.4)))
                 .setFaultTolerantExecutionMaxPartitionCount(50)
                 .setFaultTolerantExecutionMinPartitionCount(4)
                 .setFaultTolerantExecutionMinPartitionCountForWrite(50)