Remove redundant per-repo workflows in favor of centralized CI

[tillig]

Removes the per-repo workflow files (build.yml, ci.yml, dotnet-format.yml, pre-commit.yml, publish.yml) now that CI is driven by the centralized reusable workflow in autofac/.github via main.yml.

The old files and main.yml currently both run; this removes the redundant duplicates so only the shared workflow remains.

Part of the org-wide CI centralization.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 96.36%. Comparing base (0e7787c) to head (a93f1fe).

Additional details and impacted files

@@           Coverage Diff            @@
##           develop      #23   +/-   ##
========================================
  Coverage    96.36%   96.36%           
========================================
  Files            4        4           
  Lines          110      110           
  Branches        20       20           
========================================
  Hits           106      106           
  Misses           1        1           
  Partials         3        3           

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