[AI-4964] Fix process isolation to handle complex string formats and external tags

[sarah-witt]

What does this PR do?

Makes some fixes to process isolation (running a check in a new separate process) , including:

• handling string formatting in logs
• handling setting external tags

Motivation

When QAing the vSphere check with process_isolation, I encountered some errors

This is the first step to address https://datadoghq.atlassian.net/browse/AGENT-15707

Review checklist (to be filled by reviewers)

• Feature or bugfix MUST have appropriate tests (unit, integration, e2e)
• Add the qa/skip-qa label if the PR doesn't need to be tested during QA.
• If you need to backport this PR to another branch, you can add the backport/<branch-name> label to the PR and it will automatically open a backport PR once this one is merged

[codecov]

Codecov Report

❌ Patch coverage is 58.33333% with 15 lines in your changes missing coverage. Please review.
✅ Project coverage is 90.46%. Comparing base (79e0762) to head (14c88e1).
⚠️ Report is 12 commits behind head on master.

Additional details and impacted files

🚀 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.

[sarah-witt]

we could either pass or just return here