Updated tests q431 for Tier0ChainTests

The three q431 tests are updated for Tier0ChainTests:

• the number of events to run over is increased from 25 to 1000
• the number of threads is increased from 1 to 2 for the test_q431_mt

The changes are needed to catch problems at an early stage for Release 22 migration.

Adding @amete and @rmazini to follow up from their side.