Improved user logging for dependent equations search, and parallel simplex

[jajhall]

Description

Dependent equations search in presolve produced a logging line that is only relevant to developers, so logging has been rationalised so that a simple line is given via highsLogUser and the original line is given via highsLogDev (when log_dev_level > 0).

Prompted by testing #3233, I realised that we give no explanation why parallel=on does not result in parallel dual simplex being run. It used to trigger the use of parallel dual simplex if simplex_strategy=kSimplexStrategyDual or simplex_strategy=kSimplexStrategyChoose, but now parallel simplex is only used if simplex_strategy=kSimplexStrategyDualTasks or simplex_strategy=kSimplexStrategyDualMulti. This is because users will be setting parallel=on to get the parallel MIP solver, and we don't want them running parallel dual simplex as a result - since it's less robust and typically is little faster than serial. Hence a logging line has been added to flag up the change in behaviour.

Checklist

• I have read the contributing guidelines
• This PR targets the latest branch
• Tests are passing
• Documentation was updated where relevant
• This PR is not primarily AI-generated (per the AI contributions policy in CONTRIBUTING.md)

[codecov]

Codecov Report

❌ Patch coverage is 77.50000% with 9 lines in your changes missing coverage. Please review.
✅ Project coverage is 73.22%. Comparing base (3750126) to head (a04700b).
⚠️ Report is 56 commits behind head on latest.

Files with missing lines	Patch %	Lines
highs/presolve/HPresolve.cpp	76.92%	6 Missing ⚠️
highs/simplex/HEkk.cpp	78.57%	3 Missing ⚠️

Additional details and impacted files

@@           Coverage Diff           @@
##           latest    #3238   +/-   ##
=======================================
  Coverage   73.21%   73.22%           
=======================================
  Files         445      445           
  Lines      107993   108053   +60     
  Branches    17316    17320    +4     
=======================================
+ Hits        79069    79121   +52     
- Misses      28648    28656    +8     
  Partials      276      276           

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