Cancel activity when eager execution and request cancellation are in the same WFT

[yycptt]

What changed?

• Cancel activity instead of returning an activity task to worker when schedule activity with eager execution command and request cancellation command are in the same workflow task.
• Rename the feature flag from local dispatch to eager execution

Why?

• Match the behavior when eager execution is disabled.
• Basically change the behavior of eager execution + cancel from performing operation schedule + start + cancel to schedule + cancel + start (no-op), so that activity will be cancelled instead of started and returned to worker.

How did you test it?

• Added unit test

Potential risks

• N/A, sdk is still development the feature?

Is hotfix candidate?

• yes.

[yycptt]

Should be ok as this is an experimental feature and sdk side is still developing?

[yiminc]

The behavior without eager execution is schedule + cancel, there is no started event.
We should keep the same behavior when eager execution is enabled, there should be no started event.

[yycptt]

The behavior without eager execution is schedule + cancel, there is no started event. We should keep the same behavior when eager execution is enabled, there should be no started event.

This is what this pr is doing: cancel instead of start the activity and return it to worker.
Schedule + cancel without eager execution: activity scheduled + cancel requested + cancelled
Existing schedule + cancel with eager execution: activity scheduled + activity started + cancel requested and returns activity task to worker
With this change schedule + cancel with eager execution will behave the same as without eager execution.