## What changed?
Added a "soft timeout" (language used by Workflow Update) to
`GetWorkflowExecutionHistory` long polls.
## Why?
We don't want to terminate the long poll connection but instead keep it
alive by sending a response back just before the timeout. The idea is
that this will prevent connections from opening/terminating repeatedly
(ie connection churn).
## How did you test it?
- [ ] built
- [x] run locally and tested manually
- [x] covered by existing tests
- [ ] added new unit test(s)
- [ ] added new functional test(s)
## Potential risks
I was only able to verify this manually by forcing a timeout in the
server and verifying that instead of a deadline exceeded I saw a result.
I'll assume this will work since the existing code already tried doing
just exactly that, but it didn't do it well.
