build: move istio out of repo

[spacewander]

Fix #768

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 87.58%. Comparing base (715dd41) to head (b47198b).
Report is 5 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #772      +/-   ##
==========================================
- Coverage   87.70%   87.58%   -0.13%     
==========================================
  Files         136      136              
  Lines        8157     8157              
==========================================
- Hits         7154     7144      -10     
- Misses        782      789       +7     
- Partials      221      224       +3     

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[github-actions]

👋 Hi, I detected conflicts against the base branch 🙊
You'll want to sync 🔄 your branch with upstream!