Avoid showing new windows on Windows

[gaborbernat]

Resolves #1928.

[codecov]

Codecov Report

Merging #1929 into master will decrease coverage by 8.82%.
The diff coverage is 66.66%.

@@            Coverage Diff             @@
##           master    #1929      +/-   ##
==========================================
- Coverage   93.96%   85.13%   -8.83%     
==========================================
  Files          86       86              
  Lines        4225     4225              
==========================================
- Hits         3970     3597     -373     
- Misses        255      628     +373     

Flag	Coverage Δ
#tests	85.13% <66.66%> (-8.83%)	⬇️

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Impacted Files	Coverage Δ
src/virtualenv/seed/wheels/periodic_update.py	98.56% <50.00%> (-0.48%)	⬇️
src/virtualenv/util/subprocess/__init__.py	88.88% <100.00%> (-11.12%)	⬇️
src/virtualenv/discovery/windows/pep514.py	0.00% <0.00%> (-100.00%)	⬇️
src/virtualenv/discovery/windows/__init__.py	0.00% <0.00%> (-100.00%)	⬇️
src/virtualenv/util/subprocess/_win_subprocess.py	0.00% <0.00%> (-95.09%)	⬇️
src/virtualenv/util/path/_pathlib/via_os_path.py	0.00% <0.00%> (-91.51%)	⬇️
src/virtualenv/create/via_global_ref/store.py	50.00% <0.00%> (-40.00%)	⬇️
src/virtualenv/activation/batch/__init__.py	66.66% <0.00%> (-33.34%)	⬇️
.../create/via_global_ref/builtin/cpython/cpython3.py	67.39% <0.00%> (-28.27%)	⬇️
src/virtualenv/info.py	77.50% <0.00%> (-22.50%)	⬇️
... and 13 more

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[pradyunsg]

@gaborbernat Anything blocking the merge on this?