The mehari wrapper for new versions (>=0.25) needs to always run bcftools norm

[Nicolai-vKuegelgen]

Describe the bug
Mehari generally requires vcf files to not have multi-allelic variants, which can be removed by a bcftools norm call.
The current wrapper does this only when the input vcf file is also restricted to a given bed file, and the current mehari version (0.21.1) does not seem to fail on all multi-allelic variants, so it works. Soon, we will need to update the mehari version though.

To Reproduce
Steps to reproduce the behavior:

1. (Manually) update mehari version to >= 0.25.5
2. Run varfish-export step without using a bed file

Expected behavior
The mehari wrapper should always run bcftools norm.

[Nicolai-vKuegelgen]

Note: actually the current mehari wrapper does not split multiallelic at all (bcftools norm -m-)

[Nicolai-vKuegelgen]

Addendum: the snappy (g)vcf files contain the "AS_UNIQ_ALT_READ_COUNT" INFO field, which causes Problems when running bcftools norm -m-

See also: related issues and field description. It might be best to disbale/remove this field from snappy output