Support for protobuf 4.X

[jduan]

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Is your feature request related to a problem? Please describe.
Protobuf 4.X was released in Q1 2024 and many open source projects are migrating to that. I noticed that some libs under the umbrella of "google-cloud-java" still works only with protobuf 3.X. For example, com.google.cloud:google-cloud-dlp only works with protobuf-java 3.X.

Is there a plan to migrate to protobuf 4.X?

Describe the solution you'd like
What you want to happen.

Describe alternatives you've considered
Any alternative solutions or features you've considered.

Additional context
Any other context or screenshots about the feature request.