[WIP] Fix failing GitHub Actions job lint-go

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Fix the failing GitHub Actions job "lint-go"
Analyze the Actions logs, identify the root cause of the failure, and implement a fix.
Check run ID: 76872917535
Job URL: https://github.com/github/gh-aw/actions/runs/26136555318/job/76872917535

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Pull request overview

This PR addresses CI failures by removing a now-unnecessary Go test loop-variable copy (to satisfy current Go/lint semantics) and aligning Datadog MCP config header interpolation with the expected DD_APPLICATION_KEY environment variable.

Changes:

• Remove redundant tt := tt rebinding in a parallel subtest loop to satisfy copyloopvar/Go 1.25+ range semantics.
• Update Datadog MCP server config templates in workflow lockfiles to use ${DD_APPLICATION_KEY} instead of ${DD_APP_KEY} for the DD_APPLICATION_KEY header.

Show a summary per file

File	Description
pkg/cli/fetch_json_naming_test.go	Removes redundant loop-variable rebinding that can trigger copyloopvar under the repo’s Go/lint configuration.
.github/workflows/smoke-otel-backends.lock.yml	Fixes Datadog header env-var interpolation to use DD_APPLICATION_KEY.
.github/workflows/mcp-inspector.lock.yml	Fixes Datadog header env-var interpolation to use DD_APPLICATION_KEY.

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• Files reviewed: 3/3 changed files
• Comments generated: 0