Untrusted Validator Squelching - Extends squelching to limit untrusted validator message propagation

[Tapanito]

This feature improves network efficiency by limiting message propagation from untrusted validators.

Squelching currently reduces the volume of duplicate messages from validators but does not address the volume of unique messages from untrusted validators, who may not contribute meaningfully to network progress.

This change introduces a bounded number of slots for untrusted validators, selected based on unique message frequency and quantity. Once selected, their duplicate messages are subject to standard squelching logic, thereby reducing overall message overhead without impacting trusted validator performance.

High Level Overview of Change

Context of Change

Type of Change

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)
• Refactor (non-breaking change that only restructures code)
• Performance (increase or change in throughput and/or latency)
• Tests (you added tests for code that already exists, or your new feature included in this PR)
• Documentation update
• Chore (no impact to binary, e.g. .gitignore, formatting, dropping support for older tooling)
• Release

API Impact

• Public API: New feature (new methods and/or new fields)
• Public API: Breaking change (in general, breaking changes should only impact the next api_version)
• libxrpl change (any change that may affect libxrpl or dependents of libxrpl)
• Peer protocol change (must be backward compatible or bump the peer protocol version)

[codecov]

Codecov Report

Attention: Patch coverage is 46.81818% with 117 lines in your changes missing coverage. Please review.

Project coverage is 78.6%. Comparing base (9e1fe9a) to head (2a9c386).

Files with missing lines	Patch %	Lines
src/xrpld/overlay/Slot.h	60.1%	67 Missing ⚠️
src/xrpld/overlay/detail/OverlayImpl.cpp	0.0%	34 Missing ⚠️
src/xrpld/overlay/detail/PeerImp.cpp	0.0%	15 Missing ⚠️
src/xrpld/overlay/Squelch.h	0.0%	1 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff            @@
##           develop   #5399     +/-   ##
=========================================
- Coverage     78.7%   78.6%   -0.1%     
=========================================
  Files          816     816             
  Lines        70542   70667    +125     
  Branches      8284    8335     +51     
=========================================
+ Hits         55494   55551     +57     
- Misses       15048   15116     +68     

Files with missing lines	Coverage Δ
src/xrpld/core/Config.h	85.7% <ø> (ø)
src/xrpld/core/detail/Config.cpp	75.9% <100.0%> (+0.1%)	⬆️
src/xrpld/overlay/detail/OverlayImpl.h	38.4% <ø> (ø)
src/xrpld/overlay/Squelch.h	69.6% <0.0%> (ø)
src/xrpld/overlay/detail/PeerImp.cpp	3.7% <0.0%> (-<0.1%)	⬇️
src/xrpld/overlay/detail/OverlayImpl.cpp	34.0% <0.0%> (-0.7%)	⬇️
src/xrpld/overlay/Slot.h	74.9% <60.1%> (-9.9%)	⬇️

... and 5 files with indirect coverage changes

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