Update/fix/add tests for puppet-related flow (preassign+match)

[mna]

Related to #17842.

• Added/updated tests

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 65.66%. Comparing base (8253e77) to head (2cbbec0).
Report is 1 commits behind head on feat-prefill-account-name.

Additional details and impacted files

@@                      Coverage Diff                      @@
##           feat-prefill-account-name   #17859      +/-   ##
=============================================================
+ Coverage                      65.64%   65.66%   +0.01%     
=============================================================
  Files                           1194     1194              
  Lines                         108293   108272      -21     
  Branches                        2574     2574              
=============================================================
+ Hits                           71094    71100       +6     
+ Misses                         31801    31782      -19     
+ Partials                        5398     5390       -8     

Flag	Coverage Δ
backend	66.67% <100.00%> (+0.02%)	⬆️

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[mna]

I also plan to adjust/add to the existing puppet-flow integration tests, but I'll do that in yet another PR as this one has non-test fixes that should be merged ASAP in the feature branch.

[mna]

This was an existing test that was skipped due to the circular imports issue that is solved here via the external test approach (package service_test), and the tests have been adjusted to the updated implementation using ApplyTeamSpec.