Hide local timezone from VMs with specific tag

[strategictraveler]

Set fake timezone for VMs with the "anon-timezone" tag. Fixes QubesOS/qubes-issues#8381

[codecov]

Codecov Report

Attention: Patch coverage is 66.66667% with 1 line in your changes missing coverage. Please review.

Project coverage is 69.31%. Comparing base (6935f26) to head (a5dd3ba).
Report is 4 commits behind head on main.

Files with missing lines	Patch %	Lines
qubes/vm/qubesvm.py	66.66%	1 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #632      +/-   ##
==========================================
- Coverage   69.31%   69.31%   -0.01%     
==========================================
  Files          58       58              
  Lines       11994    11996       +2     
==========================================
+ Hits         8314     8315       +1     
- Misses       3680     3681       +1     

Flag	Coverage Δ
unittests	69.31% <66.66%> (-0.01%)	⬇️

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[marmarek]

Looks good but please add a test for this, see https://github.com/QubesOS/qubes-core-admin/blob/main/qubes/tests/vm/qubesvm.py, especially look at some with "qdb" in name.

[strategictraveler]

I'll look at it this weekend.