Enable SDK flag `DETERMINISTIC_CANCELLATION_SCOPE_ORDER`

[maciejdudko]

#2512 added SDK flag DETERMINISTIC_CANCELLATION_SCOPE_ORDER to resolve NDE bug in #2473. It was decided to delay enabling the flag for 2 minor releases.

We need to enable DETERMINISTIC_CANCELLATION_SCOPE_ORDER flag for all new workflows, by adding it to WorkflowStateMachines.initialFlags. We need to add a test to ensure existing workflows aren't affected by this flag. One way to test it is to use raw WorkflowService API to manually poll the workflow task and respond without setting the flag, then letting the actual worker take over the rest of the execution.