Remove deprecated windows package building scripts.

[NlightNFotis]

The scripts removed are from an early attempt to build
and package a CBMC distribution on windows, that has
now been deprecated since we delegate to CMake (CPack)
to build a windows installer.

• Each commit message has a non-empty body, explaining why the change was made.
• Methods or procedures I have added are documented, following the guidelines provided in CODING_STANDARD.md.
• The feature or user visible behaviour I have added or modified has been documented in the User Guide in doc/cprover-manual/
• Regression or unit tests are included, or existing tests cover the modified code (in this case I have detailed which ones those are in the commit message).
• My commit message includes data points confirming performance improvements (if claimed).
• My PR is restricted to a single feature or bugfix.
• White-space or formatting changes outside the feature-related changed lines are in commits of their own.

[thomasspriggs]

Should the .github/workflows/debian and .github/workflows/macos15 directories go as well?

[martin-cs]

Seems reasonable but it would be good to have someone who is a windows user comment on this. Were these scripts used for anything else apart from CI?

[NlightNFotis]

@martin-cs We have talked (offline) to the original contributor of these scripts, and unless I'm badly mistaken he agreed to us removing them.

Yes, also these scripts where only used on CI - we now have them substituted with the ones in .github/workflows/release-packages.yaml.

[NlightNFotis]

@thomasspriggs Maybe, but as a part of another PR 👍

[martin-cs]

@NlightNFotis Great! Thanks.

[codecov]

Codecov Report

Merging #5535 into develop will not change coverage.
The diff coverage is n/a.

@@           Coverage Diff            @@
##           develop    #5535   +/-   ##
========================================
  Coverage    68.52%   68.52%           
========================================
  Files         1187     1187           
  Lines        98265    98265           
========================================
  Hits         67339    67339           
  Misses       30926    30926           

Flag	Coverage Δ
#cproversmt2	42.96% <ø> (ø)
#regression	65.68% <ø> (ø)
#unit	32.26% <ø> (ø)

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[NlightNFotis]

Also, ignore the codecov project, the report seems to be spurious - this PR doesn't add or remove coverage - it's only removing CI config files.