fix: waiting for completion in TBX mode

- use testTaskCountReady method to check TaskCount value
- download all allocations when TaskCount is ready

Signed-off-by: Dunajski, Bartosz <bartosz.dunajski@intel.com>

opencl/test/unit_test/mocks/mock_command_queue.h

@@ -262,6 +262,7 @@ class MockCommandQueueHw : public CommandQueueHw<GfxFamily> {
     using BaseClass::getDevice;
     using BaseClass::gpgpuEngine;
     using BaseClass::isBlitAuxTranslationRequired;
+    using BaseClass::isCompleted;
     using BaseClass::latestSentEnqueueType;
     using BaseClass::minimalSizeForBcsSplit;
     using BaseClass::obtainCommandStream;