fix(tests): mock remote services for invoice tests

[nijel]

This avoids failres when VIES is unavaiable.

[codecov]

Codecov Report

❌ Patch coverage is 97.22222% with 1 line in your changes missing coverage. Please review.
✅ Project coverage is 81.19%. Comparing base (2222e65) to head (77b6ea0).
⚠️ Report is 1 commits behind head on main.
✅ All tests successful. No failed tests found.

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #3350      +/-   ##
==========================================
+ Coverage   81.10%   81.19%   +0.08%     
==========================================
  Files          64       64              
  Lines        6728     6763      +35     
  Branches      701      702       +1     
==========================================
+ Hits         5457     5491      +34     
  Misses       1013     1013              
- Partials      258      259       +1     

🚀 New features to boost your workflow:

• 📦 JS Bundle Analysis: Save yourself from yourself by tracking and limiting bundle sizes in JS merges.