VAI Provider - Run completion Error Cycle on missing labels

[grahamia]

Is your feature request related to a problem? Please describe.
If a run in Vertex AI is manually created and misses the required labels of runconfiguration-name or run-name the completion event in the VAI provider is created and sent to the webhook of the KFP Operator with nil for both RunConfigurationName and RunName in the run completion event data which the operator then rejects returning a 400 status error.

Describe the solution you'd like
The VAI provider should validate the request before sending to KFP Operator.
The following could be validated as mandatory:

• Status
• PipelineName
• RunConfigurationName or RunName
• RunId
• Provider

The event should be logged and acked off pubsub to clear the broken event. This will be reported in metrics covered by #421

Describe alternatives you've considered
Could do nothing as event will expire off pubsub, it doesn't break anything.