Add test for time-bar aggregation

[stefansimik]

Pull Request

With @faysou , we made an excellent team today and divided the tasks between us.

• while @faysou was focusing on the fix PR#2930
• I prepared the test in the meantime, that should ensure any similar problem will detected easily in the future

This test fails and indicates problem when composite bars aggregation stops working.

Type of change

Just new test

How has this change been tested?

Describe how this code was/is tested.

• before @faysou's fix - the test "successfully" fails and indicates that there's any problem with bar aggregation that stopped working
• after @faysou's fix - the test runs smoothly

[faysou]

Thanks for this, the test looks good. I was thinking it's hard to piece together all components together for testing this properly, but the way you do with the low level API and using the experience from your examples works well instead.