What does this PR do?

Reduces unnecessary Go CI Visibility additional-feature wrapper usage while preserving Test Management, Early Flake Detection, Flaky Test Retry, and attempt-to-fix behavior.

This PR adds an effective additional-feature selector before runTestWithRetry so tests only enter retry isolation when a feature can actually affect that test. It routes disabled tests without attempt-to-fix through a lightweight metadata/skip path, avoids retry wrappers for exact Test Management matches where all directive values are false, and keeps session-level additional-feature initialization intact before early returns.

It also tightens feature ownership rules:

• disabled and quarantined tests without attempt-to-fix no longer let EFD or FTR own retry behavior
• attempt-to-fix takes precedence over EFD/FTR for retry count, scheduler selection, retry reason, and final result propagation
• subtests with exact all-false metadata can clear inherited attempt-to-fix retry-control metadata without losing inherited disabled/quarantine state
• internal parallel EFD now uses an effective post-first-execution decision, installs a real mutex only for the bounded parallel branch, and no longer lets the raw environment flag leak into isEfdInParallel

No new environment variables are introduced; the implementation keeps using the existing internal parallel EFD flag.

Motivation

The Go CI Visibility wrapper can perturb scheduling-sensitive tests because retry-capable executions clone testing.T, run the test body in an extra goroutine, and can add retry or parallel retry scheduling. Some tests entered that heavy path only because a feature was globally enabled or because an exact Test Management record existed, even when no active directive or effective retry budget applied to the specific test.

The goal is to keep normal tests on the normal Go testing path, keep disabled tests from executing when they do not need attempt-to-fix, and avoid stacking unrelated retry behavior on top of Test Management semantics.

Testing

• go test -count=1 ./internal/civisibility/integrations/gotesting
• go test -count=1 ./internal/civisibility/integrations/gotesting/subtests
• go test -count=1 ./internal/civisibility/integrations/gotesting/failnow
• go test -count=1 ./internal/civisibility/integrations
• go test -count=1 ./internal/env
• go run ./scripts/configinverter/main.go check
• git diff --check
• Verified the rejected EFD kill switch and parallel EFD max-concurrency environment variables are not present in internal/civisibility or internal/env.

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 make lint locally.
• New code doesn't break existing tests. You can check this by running make test locally.
• Add an appropriate team label so this PR gets put in the right place for the release notes.
• All generated files are up to date. You can check this by running make generate locally.
• Non-trivial go.mod changes, e.g. adding new modules, are reviewed by @DataDog/dd-trace-go-guild. Make sure all nested modules are up to date by running make fix-modules locally.