fix(cfg): restore default http1 protocol and disable grpc-by-default optimization

[dangarhs]

Description

• Restore default: "http1" for gcs-connection.client-protocol in cfg/params.yaml and disallow empty "" protocol unmarshaling in cfg/types.go.
• Remove the machine-based-optimization (high-performance / gke-only: true) from gcs-connection.enable-grpc-by-default in cfg/params.yaml and regenerate cfg/config.go and cfg/config_test.go.
• Restore test assertions in cfg/optimize_test.go, cmd/config_validation_test.go, cmd/datatypes_parsing_test.go, and cmd/root_test.go to match the pre-grpc-default-on baseline.

Link to the issue in case of a bug fix.

NA

Testing details

1. Manual - Verified make build (go generate, go vet, golangci-lint) passes cleanly.
2. Unit tests - Passed make test across all packages in the repository.
3. Integration tests - In progress.

Any backward incompatible change? If so, please explain.

No

[gemini-code-assist]

Code Review

This pull request removes the 'gcs-connection.enable-grpc-by-default' optimization rules and associated tests. Additionally, it changes the default value of the 'client-protocol' flag from an empty string to 'http1', updating the corresponding configuration parsing, validation, and tests. I have no feedback to provide as there are no review comments.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 84.89%. Comparing base (cdc5693) to head (4f797ec).
⚠️ Report is 2 commits behind head on master.

Additional details and impacted files

@@             Coverage Diff             @@
##           master    #5155       +/-   ##
===========================================
+ Coverage        0   84.89%   +84.89%     
===========================================
  Files           0      178      +178     
  Lines           0    19638    +19638     
===========================================
+ Hits            0    16671    +16671     
- Misses          0     2966     +2966     
- Partials        0        1        +1     

Flag	Coverage Δ
unittests	84.89% <ø> (?)

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