v1.2.1: Update the container labels in the integration tests (#1588)

We've recently changed the labels for the containers, as part of unifying the
training and inference containers. This meant that certain container verification
scripts were not getting run appropriately

v1.2.0: Document the change to three containers (#1581)

Beginning with the 22.06 release, the Merlin
team provides the following three containers
that are capable of training and inference:

* `merlin-hugectr`
* `merlin-tensorflow`
* `merlin-pytorch`

This is a change from the 22.05 release that
used six containers--one for training and a
separate container for inference.

Remove step to install JupyterLab

v1.1.1: Fix install model_config_pb2.py (#1538)

We are generating the model_config_pb2.py file from a protobuf script,
but doing this as part of the 'build_ext' phase - running at the same
time as building our native extensions. This caused the build to not
pick up the generated python file unless it already existed.

Fix by moving the proto generation to the correct 'build_py' phase

v1.1.0: remove horovod example, no longer supported (#1530)

* remove horovod example, no longer supported

* rm pytorch notebook in multigpu examples

* remove record of pytorch horovod

* remove notebook for toc

* remove horovod tests for pytorch

Co-authored-by: Karl Higley <[email protected]>