Improve the error messages in quantit_excel_to_udf

[Karl-Svard]

Lims Issue

For definitions of headings below see Basic Concepts.

Work Flow: Almost all
Protocol: Almost all QC protocols
Step: Quantit steps

Description:
The error handling of the new Quantit parser needs some improvements as we currently won't catch samples that are missing in the result file. The script was originally planned to have it but the implementation was incorrect and thus required a temporary hotfix, see https://github.com/Clinical-Genomics/cg_lims/pull/578/files