STYLE: Use generate in tests, assigning values from vnl_sample_uniform

[N-Dekker]

Did find code like:

v[0] = static_cast<T>(vnl_sample_uniform(a, b));
v[1] = static_cast<T>(vnl_sample_uniform(a, b));
v[2] = static_cast<T>(vnl_sample_uniform(a, b));

And replaced it with the equivalent std::generate call:

std::generate(v.begin(), v.end(), [] {
  return static_cast<T>(vnl_sample_uniform(a, b));
});

Aims to reduce code redundancy.

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Motivation: in a follow-up I would like those vnl_sample_uniform calls to be replaced with modern C++ random number generation. This pull request should pave the way.

[hjmjohnson]

@N-Dekker It would be good to start deprecating the exposure of vnl capabilities when better alternatives exist.

[N-Dekker]

@N-Dekker It would be good to start deprecating the exposure of vnl capabilities when better alternatives exist.

• @hjmjohnson Here is a small step in that direction: pull request ENH: Replace "vnl/vnl_sample.h" with <random>, in Core tests #5611