CI: Install a fresh python virtual env every time (Linux)

[osteffenrh]

Description

Install a fresh python virtual environment every time to ensure
correct permissions and compatibility of the packages.
This is more robust than relying on being able to upgrade
an existing one.

pip upgrades are currently failing due to incorrect file permissions
in the container image virtual environment.

Let's not make use of the venv in the container and set up a fresh one
each time.

• Breaking change?
  • Breaking change - Does this PR cause a break in build or boot behavior?
  • Examples: Does it add a new library class or move a module to a different repo.
• Impacts security?
  • Security - Does this PR have a direct security impact?
  • Examples: Crypto algorithm change or buffer overflow fix.
• Includes tests?
  • Tests - Does this PR include any explicit test code?
  • Examples: Unit tests or integration tests.

How This Was Tested

Test CI runs, for example #10796

Integration Instructions

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Non-collaborators requested:

• @Javagedes

Attn Admins:

• @jljusten
• @ardbiesheuvel
• @lgao4
• @mdkinney
• @makubacki
• @jkmathews
• @miki-intel-work

---

Admin Instructions:

• Add the non-collaborators as collaborators to the appropriate team(s) listed in teams
• If they are no longer needed as reviewers, remove them from Maintainers.txt

[Javagedes]

I'll preface with the fact I have no problem with this (and my approval of the PR shows that too); however, I just want to understand the problem a little more. What is the use case in which upgrading/installing dependencies is failing? Are there CI pipelines in which this is happening, or is this internal usage of the edk2 container? If so what's the different use case that it's failing there then here?

[makubacki]

I'll preface with the fact I have no problem with this (and my approval of the PR shows that too); however, I just want to understand the problem a little more. What is the use case in which upgrading/installing dependencies is failing? Are there CI pipelines in which this is happening, or is this internal usage of the edk2 container? If so what's the different use case that it's failing there then here?

It is to unblock #10795. Issue was originally filed in the container repo but that was just to track the issue with the container it appears in. The solution here in edk2 is fine to me because outside the pipeline local users should be running as root in the container and/or can set up their own virtual env.

tianocore/containers#107