Changing the 449 retry policy to force back-off even on initial retry and start with shorter back-offs (Azure#16473)

* Reafactoring GoneAndRetryWithRetryPolicy

* Removing separate classes

* Fixing compile time issue

* Iterating on 449 change

* Fixing test regressions

* Adding unit tests

* Reacting to CR feedback

* Reacting to CR feedback

Author: FabianMeiswinkel