Modify optimtest to perform less function evaluations

[leburgel]

Small tweak to the optimtest to perform less function evaluations (2/3 of the amount it currently performs). This is quite handy when testing things for which evaluations are expensive.

[codecov-commenter]

Codecov Report

❌ Patch coverage is 0% with 13 lines in your changes missing coverage. Please review.
✅ Project coverage is 82.38%. Comparing base (e476e82) to head (61a67b0).

Files with missing lines	Patch %	Lines
src/OptimKit.jl	0.00%	13 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##           master      #24      +/-   ##
==========================================
+ Coverage   82.06%   82.38%   +0.32%     
==========================================
  Files           5        5              
  Lines         513      511       -2     
==========================================
  Hits          421      421              
+ Misses         92       90       -2     

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[Jutho]

That was indeed pretty stupid in the original design.

[Jutho]

Thanks. This is indeed a much more sensible approach.