fix: keep idle validation on global timers

[mcollina]

Summary

• backport fix: keep idle validation on global timers #5407 to v7.x
• restore idle socket validation to use the normal global timer APIs instead of bypassing fake timers through node:timers
• update cache interceptor tests to fake only Date, which is the only clock behavior they need to control

Tests

• node --test test/interceptors/cache.js
• node --test test/response-queue-poisoning.js test/issue-810.js
• npm run lint -- --quiet

[codecov-commenter]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 92.88%. Comparing base (8e4046e) to head (1bd3bf9).

Additional details and impacted files

@@            Coverage Diff             @@
##             v7.x    #5409      +/-   ##
==========================================
- Coverage   92.88%   92.88%   -0.01%     
==========================================
  Files         112      112              
  Lines       35912    35911       -1     
==========================================
- Hits        33357    33356       -1     
  Misses       2555     2555              

☔ View full report in Codecov by Harness.
📢 Have feedback on the report? Share it here.

🚀 New features to boost your workflow:

• ❄️ Test Analytics: Detect flaky tests, report on failures, and find test suite problems.
• 📦 JS Bundle Analysis: Save yourself from yourself by tracking and limiting bundle sizes in JS merges.