Remove Restic build from Dockerfile, Makefile and Tiltfile.

[blackpiglet]

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Does your change fix a particular issue?

Fixes #9490

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• Accepted the DCO. Commits without the DCO will delay acceptance.
• Created a changelog file (make new-changelog) or comment /kind changelog-not-required on this PR.
• Updated the corresponding documentation in site/content/docs/main.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 60.97%. Comparing base (4d9bd91) to head (39db9f9).
⚠️ Report is 3 commits behind head on main.

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #9728   +/-   ##
=======================================
  Coverage   60.97%   60.97%           
=======================================
  Files         384      384           
  Lines       36609    36609           
=======================================
+ Hits        22322    22324    +2     
+ Misses      12678    12677    -1     
+ Partials     1609     1608    -1     

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