feat: use built-in venv, prevent silent failures, avoid pip compatibility issues, and ensure cleanup even if deactivate fails

[immanuwell]

Summary

Improvements in script installer/build-linux.sh

Changes

Changes in installer/build-linux.sh:

• ensure exit on errors, undefined variables, and pipe failures
• use the built-in venv module, removing an external dependency (virtualenv)
• ensure you're using a recent pip version, avoiding potential compatibility issues
• suppresses errors if deactivate fails (which can happen in non-interactive shells)

Testing

I carefully tested this new version of installer/build-linux.sh a few times

Checklist

• Read the contributions page.
• Submitted the CLA form, if you are a first time contributor.
• The introduced changes are covered by unit and/or integration tests.

@ktsakalozos fyi