chore(hiding_ci): fix up guest_memfd UFFD patches

[kalyazin]

Changes

• Update the guest_memfd UFFD fixup patch
• Remove doc and test patches committed by mistake last time

Reason

A bug in guest_memfd UFFD patches preventing registering UFFD on an anon memory.

License Acceptance

By submitting this pull request, I confirm that my contribution is made under
the terms of the Apache 2.0 license. For more information on following Developer
Certificate of Origin and signing off your commits, please check
CONTRIBUTING.md.

PR Checklist

• I have read and understand CONTRIBUTING.md.
• I have run tools/devtool checkstyle to verify that the PR passes the
  automated style checks.
• I have described what is done in these changes, why they are needed, and
  how they are solving the problem in a clear and encompassing way.
• [ ] I have updated any relevant documentation (both in code and in the docs)
  in the PR.
• [ ] I have mentioned all user-facing changes in CHANGELOG.md.
• [ ] If a specific issue led to this PR, this PR closes the issue.
• [ ] When making API changes, I have followed the
  Runbook for Firecracker API changes.
• [ ] I have tested all new and changed functionalities in unit tests and/or
  integration tests.
• [ ] I have linked an issue to every new TODO.

---

• This functionality cannot be added in rust-vmm.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 82.73%. Comparing base (90dca9a) to head (f686d60).
Report is 1 commits behind head on feature/secret-hiding.

Additional details and impacted files

@@                    Coverage Diff                    @@
##           feature/secret-hiding    #5167      +/-   ##
=========================================================
+ Coverage                  82.72%   82.73%   +0.01%     
=========================================================
  Files                        251      251              
  Lines                      27522    27522              
=========================================================
+ Hits                       22768    22771       +3     
+ Misses                      4754     4751       -3     

Flag	Coverage Δ
5.10-c5n.metal	83.20% <ø> (+<0.01%)	⬆️
5.10-m5n.metal	83.20% <ø> (ø)
5.10-m6a.metal	82.37% <ø> (-0.01%)	⬇️
5.10-m6g.metal	79.07% <ø> (ø)
5.10-m6i.metal	83.19% <ø> (ø)
5.10-m7a.metal-48xl	82.37% <ø> (?)
5.10-m7g.metal	79.07% <ø> (ø)
6.1-c5n.metal	83.24% <ø> (ø)
6.1-m5n.metal	83.24% <ø> (ø)
6.1-m6a.metal	82.41% <ø> (ø)
6.1-m6g.metal	79.07% <ø> (ø)
6.1-m6i.metal	83.24% <ø> (ø)
6.1-m7a.metal-48xl	82.41% <ø> (?)
6.1-m7g.metal	79.07% <ø> (ø)
6.14-c5n.metal	83.20% <ø> (?)
6.14-m5n.metal	83.21% <ø> (?)
6.14-m6a.metal	82.38% <ø> (?)
6.14-m6g.metal	79.03% <ø> (?)
6.14-m6i.metal	83.20% <ø> (?)
6.14-m7a.metal-48xl	82.38% <ø> (?)
6.14-m7g.metal	79.03% <ø> (?)

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[roypat]

I'm force-merging this one because we have a chicken-and-egg problem: It doesnt pass CI because the kernels of the buildkite runner have a bug that is introduced by the patches that we store in the feature branch. So to merge PRs, we need to fix the issue with the host kernel, but the issue is on the feature branch, and so to fix it we need to merge a PR.