Validate LRA behaviour when multiple LRA's are active on the same thread

Add tests that check that when multiple LRA's are active on the same thread that as one LRA finishes that:

• the next one is handled correctly
• creating another one still works fine

This issues relates to some suspect code at the end of the method `NarayanaLRAClient#endLRA` where the base URI of the target coordinator includes the Uid part of the LRA id.