Always preprocess reference sequences for reference size dependant parameter deduction

[eaasna]

• [x] valik split: preprocess metagenome references for parameter deduction
• [x] switch to unfiltered distributed Stellar search for high error rates
• [x] estimate k-mer (or minimiser) count for IBF bin size calculation

[codecov-commenter]

Codecov Report

Attention: Patch coverage is 94.59459% with 2 lines in your changes are missing coverage. Please review.

Project coverage is 94.44%. Comparing base (800d24f) to head (b69f432).

Files	Patch %	Lines
include/valik/split/metadata.hpp	94.59%	2 Missing :warning:

Additional details and impacted files

```diff @@ Coverage Diff @@ ## main #105 +/- ## =========================================== + Coverage 77.77% 94.44% +16.66% =========================================== Files 3 2 -1 Lines 117 72 -45 =========================================== - Hits 91 68 -23 + Misses 26 4 -22 ```

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