tests: several fixes to nested tests for UC24

[Meulengracht]

Rough summary of changes for some of the nested tests:

• Make sure we write the bootstrap wrapper for core24
• Update model for hybrid 24
• Fix how we add and check for section in kernel.efi

The remodel-min-size still needs to be fixed, will do that in a separate PR

REF: SNAPDENG-33308

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 79.03%. Comparing base (96ea7b0) to head (ce3232b).
Report is 108 commits behind head on master.

Additional details and impacted files

@@            Coverage Diff             @@
##           master   #14761      +/-   ##
==========================================
+ Coverage   78.95%   79.03%   +0.07%     
==========================================
  Files        1084     1087       +3     
  Lines      146638   147873    +1235     
==========================================
+ Hits       115773   116866    +1093     
- Misses      23667    23767     +100     
- Partials     7198     7240      +42     

Flag	Coverage Δ
unittests	79.03% <ø> (+0.07%)	⬆️

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