[projmgr] Rework debugger custom properties default handling

[grasci-arm]

Rework custom properties handling introduced in #2126

[github-actions]

Test Results

    3 files     21 suites   12m 50s ⏱️
  426 tests   426 ✅ 0 💤 0 ❌
1 278 runs  1 278 ✅ 0 💤 0 ❌

Results for commit 0204ad0.

[codecov]

Codecov Report

❌ Patch coverage is 66.66667% with 1 line in your changes missing coverage. Please review.
✅ Project coverage is 66.81%. Comparing base (4b696fb) to head (0204ad0).
⚠️ Report is 1 commits behind head on main.

Files with missing lines	Patch %	Lines
tools/projmgr/src/ProjMgrRunDebug.cpp	50.00%	1 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #2244      +/-   ##
==========================================
- Coverage   66.82%   66.81%   -0.01%     
==========================================
  Files         181      181              
  Lines       38849    38844       -5     
  Branches    22807    22804       -3     
==========================================
- Hits        25960    25954       -6     
- Misses       8079     8080       +1     
  Partials     4810     4810              

Flag	Coverage Δ
projmgr-cov	80.93% <66.66%> (-0.02%)	⬇️

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Files with missing lines	Coverage Δ
tools/projmgr/include/ProjMgrRunDebug.h	100.00% <ø> (ø)
tools/projmgr/test/src/ProjMgrUnitTests.cpp	80.24% <100.00%> (+<0.01%)	⬆️
tools/projmgr/src/ProjMgrRunDebug.cpp	86.72% <50.00%> (-0.42%)	⬇️

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