Create upgrade e2e scenario covering upgrade during training

[sutaakar]

Scenario should start a training, perform an operator upgrade during training and finish the training.

Covered features:

• ability of the new operator to process CRs created by old operator
• ability of CodeFlare SDK to connect to existing Cluster and work with AppWrapper created by previous version (i.e. one client session creates an AppWrapper, a later client session can delete/get the AppWrapper)

[sutaakar]

@astefanutti What do you think about this scenario?

[astefanutti]

@sutaakar I agree it'd be critical to assess existing operands are not affected by the upgrade, especially those that are not in terminal states.