Migrate Vertex AI Model Handler to new base class

[jrmccluskey]

Simplifies the Vertex AI model handler implementation by migrating to the new RemoteModelHandler base class. Should be a backwards-compatible change, as the args to the constructor have not changed.

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[jrmccluskey]

Green Python PostCommit run against refactored class - https://github.com/apache/beam/actions/runs/14336422141

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[liferoad]

Much cleaner. Thanks.

[senim2]

I think this was a breaking change since run_inference public method was removed.

[liferoad]

Do you directly use run_inference in VertexAIModelHandlerJSON?

[senim2]

Do you directly use run_inference in VertexAIModelHandlerJSON?

Hi, thanks for the reply. We have a use case where we customised VertexAIModelHandlerJSON by extending it and customising the behaviour inside the run_inference public method.

[liferoad]

Do you directly use run_inference in VertexAIModelHandlerJSON?

Hi, thanks for the reply. We have a use case where we customised VertexAIModelHandlerJSON by extending it and customising the behaviour inside the run_inference public method.

I see. run_inference is now the part of RemoteModelHandler. You could still customize it.