Update proto file and use new lossless error bound

[CGodiksen]

This PR updates the Apache Arrow Flight tester to match the latest changes from https://github.com/ModelarData/ModelarDB-RS.

Note that this PR should not be merged before ModelarData/ModelarDB-RS#350 is merged.

[Copilot]

Pull Request Overview

This PR updates the Apache Arrow Flight tester to use a new "lossless" error bound type and removes retention period configuration parameters, synchronizing with changes from ModelarDB-RS.

• Adds LOSSLESS error bound type to protocol definitions
• Removes retention_period_in_seconds from Configuration messages
• Updates test code to use lossless error bounds instead of absolute

Reviewed Changes

Copilot reviewed 4 out of 4 changed files in this pull request and generated 1 comment.

File	Description
protocol.proto	Adds LOSSLESS error bound type and removes retention period configuration
protocol_pb2.py	Updates generated Python protobuf code with new serialized protocol definitions
protocol_pb2.pyi	Updates Python type stubs to reflect protocol changes
common.py	Changes test table creation to use lossless error bounds

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