[jenkins] updates for migration to new k8s-based system

[dylex]

We are moving jenkins builds to a new system with more resources and flexibility. This commit will switch to allowing builds on the new system.

Once this is merged, I can remove the project on the old system.

(There's a couple other ITensor projects on the old system: ITensor and ITensorGPU.jl, but neither of these has been built in years, so I assume they're no longer needed.)

[mtfishman]

Thanks @dylex!

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 81.02%. Comparing base (ef08b6f) to head (7a24f5f).

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #1754   +/-   ##
=======================================
  Coverage   81.02%   81.02%           
=======================================
  Files          80       80           
  Lines        5074     5074           
=======================================
  Hits         4111     4111           
  Misses        963      963           

Flag	Coverage Δ
docs	4.98% <ø> (ø)

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