DBZ-8380 Migrate DB2 testsuite to async engine

[vjuranek]

https://issues.redhat.com/browse/DBZ-8380

[vjuranek]

I think these two (or batter to say IncrementalSnapshotIT) fails randomly quite often:

Error:  Failures: 
Error:    IncrementalSnapshotIT>AbstractIncrementalSnapshotTest.snapshotWithAdditionalConditionWithSurrogateKey:1036->AbstractConnectorTest.assertNoRecordsToConsume:1026 expected:<[tru]e> but was:<[fals]e>
Error:    IncrementalSnapshotIT>AbstractIncrementalSnapshotTest.snapshotWithNewAdditionalConditionsField:942->AbstractConnectorTest.assertNoRecordsToConsume:1026 expected:<[tru]e> but was:<[fals]e>
[INFO] 
Error:  Tests run: 83, Failures: 2, Errors: 0, Skipped: 3

[jpechane]

I se them failing locally now too

[vjuranek]

ok, I'll take a look (on my machine it's passing, but I haven't run it many times)

[vjuranek]

Everything passing now, thus merging.