Fix parsing of UMI tools dedup output to MultiQC

[lianov]

Description

Currently, given our strategy of splitting files by chr. to speed up deduplication, there are multiple QC files reported in the MultiQC report (one dedup QC for each chr). This will lead to over-crowding of the report with multiple samples (both in the General Stats section and UMI-tools. A few strategies around this may include:

1. Only include main chromossomes (no haplotypes etc., given lower reads in these regions). This may still be too much for the report, but worth a thought (second option more straight-forward)
2. Create a new UMI-tools stats output based on overall metrics from split files.

[lianov]

As a note, our path here for first release will be to disable the outputs from UMI-tools from being passed on to MultiQC at this time. The pipeline already produces samtools stats from before and after dedub, and although this does not provide a bar plot for the % of reads that are detected from UMI-tools, once can see how many reads are dropped from dedup from the already provided metrics (at the top of the MultiQC report).

We will leave this issue open for re-consideration in the future (and the files from UMI-tools are still produced, simply not added to the scnanoseq "out of the box" MultiQC report)