Remove definitions of unused exception classes.

It looks like those classes are not used anymore.

Change-Id: Iccf7300859339335fd13f4429b241258341d3766

tempest/exceptions.py

@@ -82,11 +82,6 @@ class AddImageException(TempestException):
     message = "Image %(image_id)s failed to become ACTIVE in the allotted time"
 
 
-class EC2RegisterImageException(TempestException):
-    message = ("Image %(image_id)s failed to become 'available' "
-               "in the allotted time")
-
-
 class VolumeBuildErrorException(TempestException):
     message = "Volume %(volume_id)s failed to build and is in ERROR status"
 
@@ -108,25 +103,10 @@ class StackBuildErrorException(TempestException):
                "due to '%(stack_status_reason)s'")
 
 
-class StackResourceBuildErrorException(TempestException):
-    message = ("Resource %(resource_name)s in stack %(stack_identifier)s is "
-               "in %(resource_status)s status due to "
-               "'%(resource_status_reason)s'")
-
-
-class AuthenticationFailure(TempestException):
-    message = ("Authentication with user %(user)s and password "
-               "%(password)s failed auth using tenant %(tenant)s.")
-
-
 class EndpointNotFound(TempestException):
     message = "Endpoint not found"
 
 
-class ImageFault(TempestException):
-    message = "Got image fault"
-
-
 class IdentityError(TempestException):
     message = "Got identity error"
 
@@ -135,10 +115,6 @@ class ServerUnreachable(TempestException):
     message = "The server is not reachable via the configured network"
 
 
-class TearDownException(TempestException):
-    message = "%(num)d cleanUp operation failed"
-
-
 # NOTE(andreaf) This exception is added here to facilitate the migration
 # of get_network_from_name and preprov_creds to tempest-lib, and it should
 # be migrated along with them