Fix incorrect exception order in _execute_request

_execute_request has a list of exception handlers to log various types
of errors with more specific error messages. Unfortunately, it catches
requests.exceptions.ConnectionError before requests.exceptions.SSLError,
but ConnectionError is a superclass of SSLError so the latter is never
invoked.

This change corrects the exception handling order, and enables the
bad-except-order pylint check now that the check passes.

Change-Id: I92bacd6088de5cbc170bc5c081a1db1baeec69e7
Closes-Bug: #1360970
Merge "Fix incorrect exception order in _execute_request"