Fix performance degradation in ignite streaming endpoint

[tyrasd]

#495 had unfortunately introduced a bug¹ in affinitycall's stream implementation which caused the backend to always use the slow fallback path (i.e. .collect().stream()). This is particularily slow for medium to large bounding boxes, as it will not use the preflight optimizations implemented for stream.

For example, this has the effect that with this version all ohsome-api data extractions are very slow.

Checklist

• My code follows the code-style rules, and I have checked on the static analyses and benchmark (if applicable) results
• I have commented my code
• I have written javadoc (required for public classes and methods)
• I have added sufficient unit tests
• I have made corresponding changes to the documentation
• I have updated the CHANGELOG.md
• I have adjusted the examples or created an issue in the corresponding repository
• I have adjusted the benchmark or created an issue in the corresponding repository

Footnotes

1. the concrete problem being that stream.toList() returns an immutable list which cannot be shuffled in the following code line, while the previously used stream.collect(Collectors.toList()) does return a mutable list (even though it does not guarantee the mutability of it, btw). ↩

[rtroilo]

thank you!