Fix np.shuffle and wrong return type in searchspace samplers

[AntonOresten]

get_distributed_random_sample_indices and get_LHS_sample_indices called the non-existent np.shuffle when num_samples == size, raising AttributeError. The distributed sampler also returned param-config tuples instead of indices when the random pool covered the whole searchspace.

Replaced with np.random.permutation(size).tolist() and get_random_sample_indices(num_samples).tolist(), and added test cases for the num_samples == size and num_samples > size paths, which were previously uncovered.

[sonarqubecloud]

Quality Gate passed

Issues
0 New issues
0 Accepted issues

Measures
0 Security Hotspots
0.0% Coverage on New Code
0.0% Duplication on New Code

See analysis details on SonarQube Cloud

[fjwillemsen]

@AntonOresten thank you for your excellent contribution to fix this corner case and preventing it from occurring in the future!