* ProxyError is derived from ConnectionError, but it's necessary
to check the Response object to identify.
- Added ProxyError in retry_if_exception_type
- Updated _post_to_inspector to proper handle ProxyError
- Updated the wait to use wait_exponential instead of wait_fixed.
Closes-Bug: 2045429
Change-Id: Iefe3fe581cd4e7c91a0da708e6f6d0fdaacab6fe