remove stray omics_type slot

[wdduncan]

In nmdc.yaml, there seems to be a stay omics_type slot that is not associated with any class:

 omics_type:
    range: string

This is not that same of the omics type slot that is used for omics processing:

omics type:
    range: controlled term value 
    description: >-
      The type of omics data
    examples:
      - value: metatranscriptome
      - value: metagenome

cc @turbomam @sujaypatil96 @cmungall @dehays

[brynnz22]

@turbomam can this be marked as closed and finished? I looked at the nmdc.yaml file and all I see is omics_type. I do not see any such omics type slot described above?

[turbomam]

Yes, thank you!