tests fail randomly (rare)

[asherikov]

e.g.,

7: [ RUN      ] DataTamerBasic.VectorWithChangingSize
7: ../../../../src/data_tamer/data_tamer_cpp/tests/dt_tests.cpp:244: Failure
7: Expected equality of these values:
7:   sink->latest_snapshot.payload.size()
7:     Which is: 0
7:   vect.size() * sizeof(float) + sizeof(uint32_t)
7:     Which is: 20

20: [ RUN      ] DataTamerBasic.SinkAdd
20: ../../../../src/data_tamer/data_tamer_cpp/tests/dt_tests.cpp:50: Failure
20: Expected equality of these values:
20:   dummy_sink_A->snapshots_count[hash]
20:     Which is: 0
20:   shapshot_count
20:     Which is: 10