chore(codecs): replace native encoding fixture patch files with cfg-gated code

[thomasqueirozb]

Summary

Replaces the loose patch files (vector_generate_fixtures.patch, vrl_generate_fixtures.patch) used to regenerate native encoding test fixtures with proper generate-fixtures feature flags in both this repo and the VRL repo, plus a standalone binary that writes fixtures directly to their committed location.

Key changes:

• generate-fixtures feature in vector-core activates fixture-stable Arbitrary impls (NaN-safe f64, non-empty names, no timestamps) and pulls in vrl/generate-fixtures automatically
• Arbitrary impls moved from test/common.rs to event/arbitrary_impl.rs, compiled under any(test, feature = "generate-fixtures")
• Sub-generators derived from parent via u64::arbitrary(g) instead of Gen::new() (which called from_entropy()) to ensure full determinism
• AgentDDSketch::set_sum_avg method gated on the feature instead of making fields pub
• Fixture generation binary (cargo run -p vector-core --features generate-fixtures --bin generate-fixtures) writes directly to lib/codecs/tests/data/native_encoding/

Vector configuration

NA

How did you test this PR?

Ran the binary twice and confirmed identical checksums. Ran cargo test -p vector-core to confirm existing tests pass.

Change Type

• Bug fix
• New feature
• Dependencies
• Non-functional (chore, refactoring, docs)
• Performance

Is this a breaking change?

• Yes
• No

Does this PR include user facing changes?

• Yes. Please add a changelog fragment based on our guidelines.
• No. A maintainer will apply the no-changelog label to this PR.

References

• Related: chore(dev): add generate-fixtures feature vrl#1711
• Related: Improve codecs testing to include special/problem values #18666

[pront]

@codex review

[chatgpt-codex-connector]

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[thomasqueirozb]

@codex review

[chatgpt-codex-connector]

Codex Review: Didn't find any major issues. 🚀

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[pront]

Approved! Those patch files were embarrassing to say the least. Thanks for replacing them with a much cleaner feature-gated approach.

Reminder to revert the VRL dependency change.