Optimize WHEA UEFI shell test

[kuqin12]

Description

The WHEA UEFI shell test currently can take up to 16 minutes to run for AArch64 platforms. 2 main reasons are:

1. The system does not support variable cache, which requires environment switching for each variable query;
2. Each WHEA tests will invoke a variable sweep cleanup, that spans from HwErrRec0000 to HwErrRecFFFF;

This PR aims at fixing the latter issue. Given the test will sequentially populate the telemetry entries, the cleanup can also be optimized to, after the first deep clean, stop at the first EFI_NOT_FOUND.

The change created a common routine to centralize all clean up functions and added a new shallow cleanup routine. By adopting shallow cleanups, the tests reduce the original 10 deep cleans down to 2, which should shorten the corresponding test time by 75% ~ 80%.

For details on how to complete these options and their meaning refer to CONTRIBUTING.md.

• Impacts functionality?
• Impacts security?
• Breaking change?
• Includes tests?
• Includes documentation?

How This Was Tested

This test is run on ARM virt platform and confirmed only 2 full cleanups and shortened to local runs to < 2min. All tests are still passing.

Integration Instructions

N/A

[mu-automation]

✅ QEMU Validation Passed

Source Dependencies

Repository	Commit
mu_plus	ae38413
mu_tiano_platforms	f584806

Results

Platform	Target	Build	Boot	Overall Boot Time	Build Logs	Boot Logs
Q35	DEBUG	✅ success	✅ success	0m 15s	Build Logs	Boot Logs
SBSA	DEBUG	✅ success	✅ success	0m 30s	Build Logs	Boot Logs

Workflow run: https://github.com/microsoft/mu_plus/actions/runs/27084483584

This comment was automatically generated by the Mu QEMU PR Validation workflow.

[codecov-commenter]

Codecov Report

✅ All modified and coverable lines are covered by tests.
⚠️ Please upload report for BASE (release/202511@f72b73c). Learn more about missing BASE report.

Additional details and impacted files

@@               Coverage Diff                @@
##             release/202511    #893   +/-   ##
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  Coverage                  ?   7.37%           
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  Files                     ?      21           
  Lines                     ?    3051           
  Branches                  ?     121           
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  Hits                      ?     225           
  Misses                    ?    2825           
  Partials                  ?       1           

Flag	Coverage Δ
MsWheaPkg	7.37% <ø> (?)

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