Clean up Docker-related files

[jwodder]

Part of #325.

[codecov-commenter]

Codecov Report

Merging #351 (ebf5379) into master (a4c1ba2) will increase coverage by 0.01%.
The diff coverage is n/a.

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@@            Coverage Diff             @@
##           master     #351      +/-   ##
==========================================
+ Coverage   33.63%   33.64%   +0.01%     
==========================================
  Files          50       50              
  Lines        7050     7047       -3     
  Branches     1781     1685      -96     
==========================================
  Hits         2371     2371              
- Misses       4500     4506       +6     
+ Partials      179      170       -9     

see 6 files with indirect coverage changes

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[yarikoptic]

I think that may be someone forgot to commit that Docker-blazegraph and in general the idea to have it since IIRC blazegraph is used by the project for graphdb. May be @albertcrowley could clarify?

[yarikoptic]

ok, for now let's proceed, and if anything - we can return needed pieces.

[github-actions]

🚀 PR was released in v4.0.0 🚀