Add a pre-flight check when pe_count > cpu_set.weight()

[dagardner-nv]

Description

• Replace the DCHECK_LE in the ReusableFiberEngineFactory class with an if/throw.
• Update ~EdgeHolder to LOG(DFATAL). The thinking here is that this error is only of use to MRC developers and not of use to downstream users (Borrowed from PR Revert partially constructed segments on-error in segment init function #434).

Checklist

• I am familiar with the Contributing Guidelines.
• New or existing tests cover these changes.
• The documentation is up to date with these changes.

[willkill07]

Functionally looks great! Just a small nit on reusing DFATAL logging level to avoid stringstream + preprocessor branching.

[dagardner-nv]

/merge

[codecov]

Codecov Report

Attention: Patch coverage is 9.52381% with 19 lines in your changes missing coverage. Please review.

Project coverage is 73.58%. Comparing base (46f92ca) to head (da8222c).
Report is 1 commits behind head on branch-25.06.

Files with missing lines	Patch %	Lines
cpp/mrc/include/mrc/edge/edge_holder.hpp	0.00%	12 Missing ⚠️
cpp/mrc/src/internal/system/device_info.cpp	0.00%	5 Missing ⚠️
cpp/mrc/src/internal/runnable/engine_factory.cpp	50.00%	2 Missing ⚠️

Additional details and impacted files

@@               Coverage Diff                @@
##           branch-25.06     #547      +/-   ##
================================================
- Coverage         73.71%   73.58%   -0.14%     
================================================
  Files               407      407              
  Lines             15122    15144      +22     
  Branches           1201     1203       +2     
================================================
- Hits              11147    11143       -4     
- Misses             3975     4001      +26     

Flag	Coverage Δ
cpp	70.51% <9.52%> (-0.14%)	⬇️
py	43.54% <9.52%> (-0.06%)	⬇️

Flags with carried forward coverage won't be shown. Click here to find out more.

Files with missing lines	Coverage Δ
cpp/mrc/src/internal/system/topology.cpp	83.85% <ø> (ø)
cpp/mrc/src/tests/test_topology.cpp	90.76% <ø> (-7.65%)	⬇️
cpp/mrc/src/internal/runnable/engine_factory.cpp	83.95% <50.00%> (-1.77%)	⬇️
cpp/mrc/src/internal/system/device_info.cpp	52.87% <0.00%> (-3.23%)	⬇️
cpp/mrc/include/mrc/edge/edge_holder.hpp	65.62% <0.00%> (-8.50%)	⬇️

... and 1 file with indirect coverage changes

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