QC pipeline currently adds both fraction_mitochondrial and pct_mitochondrial

[LucHendriks]

I ran the following pipelines:

1. cellranger multi workflow, workflows/ingestion/cellranger_multi (0.11.0)
2. qc workflow, workflows/qc/qc (main_build: 7c40bbb)

The output of the cellranger multi .h5mu:

MuData object with n_obs × n_vars = 1861136 × 32285
  var:	'gene_symbol', 'feature_types', 'genome'
  1 modality
    rna:	1861136 x 32285
      var:	'gene_symbol', 'feature_types', 'genome'

The output of the qc workflow .h5mu:

MuData object with n_obs × n_vars = 1861136 × 32285
  var:	'gene_symbol', 'feature_types', 'genome', 'mitochondrial', 'pct_dropout', 'num_nonzero_obs', 'obs_mean', 'total_counts'
  1 modality
    rna:	1861136 x 32285
      obs:	'fraction_mitochondrial', 'num_nonzero_vars', 'total_counts', 'pct_mitochondrial', 'total_counts_mitochondrial', 'pct_of_counts_in_top_50_vars', 'pct_of_counts_in_top_100_vars', 'pct_of_counts_in_top_200_vars', 'pct_of_counts_in_top_500_vars'
      var:	'gene_symbol', 'feature_types', 'genome', 'mitochondrial', 'pct_dropout', 'num_nonzero_obs', 'obs_mean', 'total_counts'

[DriesSchaumont]

I believe this will be fixed by #606, see commend #606 (comment)