feat: Regenerate libraries with protobuf-4.x

[diegomarquezp]

This PR regenerates the client libraries using protobuf code generator 4.x

[diegomarquezp]

java-asset was somehow not set to snapshot, so it was downloading the main branch's jar and failing due to runtime mismatch.

2025-12-08T22:06:12.3477387Z 22:06:12:344 [ERROR] COMPILATION ERROR : 
2025-12-08T22:06:12.3477911Z 22:06:12:345 [INFO] -------------------------------------------------------------
2025-12-08T22:06:12.3479501Z 22:06:12:345 [ERROR] /home/runner/work/google-cloud-java/google-cloud-java/java-asset/proto-google-cloud-asset-v1p1beta1/src/main/java/com/google/cloud/asset/v1p1beta1/AssetProto.java:[24,58] cannot find symbol
2025-12-08T22:06:12.3480933Z   symbol:   class GeneratedFile
2025-12-08T22:06:12.3481323Z   location: package com.google.protobuf
2025-12-08T22:06:12.3482788Z 22:06:12:345 [ERROR] /home/runner/work/google-cloud-java/google-cloud-java/java-asset/proto-google-cloud-asset-v1p1beta1/src/main/java/com/google/cloud/asset/v1p1beta1/AssetProto.java:[23,21] cannot find symbol
2025-12-08T22:06:12.3484024Z   symbol:   class Generated
2025-12-08T22:06:12.3484342Z   location: package com.google.protobuf