test(guardrails): remove redundant runtime-check unit test (#9098)

packages/dd-trace/test/guardrails/index.spec.js duplicated existing
integration coverage. init.spec.js's "when node version is too recent"
context already exercises the incompatible-runtime bailout — plus the
telemetry, debug logs, and DD_INJECT_FORCE override that the unit test
stubbed to no-ops — by setting pkg.nodeMaxMajor = NODE_MAJOR.

The unit test was added in #9033 only to satisfy a Codecov patch-coverage
flag on lines that PR added to the bailout block (integration tests run
in sandboxes and don't count toward nyc). It relied on proxyquire
intercepting an in-function require() of package.json, which is
environment-dependent: it failed on the v5.110.0 release proposal on
Node 26 even though the real bailout — verified by the passing
init.spec.js integration test on that same run — works correctly.

Co-authored-by: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

Author: 2 people