envoyproxy: fix misc jsoniter

[eliottness]

What does this PR do?

Fix misc issues with jsoniter implementation

Motivation

Reviewer's Checklist

• [ ] Changed code has unit tests for its functionality at or near 100% coverage.
• [ ] System-Tests covering this feature have been added and enabled with the va.b.c-dev version tag.
• [ ] There is a benchmark for any new code, or changes to existing code.
• [ ] If this interacts with the agent in a new way, a system test has been added.
• [ ] New code is free of linting errors. You can check this by running golangci-lint run locally.
• [ ] Add an appropriate team label so this PR gets put in the right place for the release notes.
• [ ] Non-trivial go.mod changes, e.g. adding new modules, are reviewed by @DataDog/dd-trace-go-guild.

Unsure? Have a question? Request a review!

[eliottness]

• #3643
• #3642 👈 (View in Graphite)
• main

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[pr-commenter[bot]]

Benchmarks

Benchmark execution time: 2025-06-25 10:07:02

Comparing candidate commit ddf1acc26b32e6d4494eb5765df088ef3dc3dd51 in PR branch eliottness/fix-misc-jsoniter with baseline commit d2b0acd8ca874dc61a63709b603cbc2a9c1a3493 in branch main.

Found 0 performance improvements and 0 performance regressions! Performance is the same for 24 metrics, 0 unstable metrics.

[datadog-datadog-prod-us1[bot]]

Datadog Report

Branch report: eliottness/fix-misc-jsoniter Commit report: 6c5490c Test service: dd-trace-go

:white_check_mark: 0 Failed, 70 Passed, 0 Skipped, 4m 26.27s Total Time