Remove all mappings in `custom_curies.yaml` and code using it in data source ETL pipelines

[sujaypatil96]

There are still some mappings captured in the custom_curies.yaml file here: https://github.com/Knowledge-Graph-Hub/kg-microbe/blob/master/kg_microbe/transform_utils/custom_curies.yaml but none of those mappings are being pulled into the KGX transformation output/TSV files (check for the presence/absence of curie prefixes in output).

The reason for that being the pipeline code written "defensively". For example the way it has been written here in the BacDive transformation pipeline: https://github.com/Knowledge-Graph-Hub/kg-microbe/blob/master/kg_microbe/transform_utils/bacdive/bacdive.py#L409-L505 while constructing edges using information from "keywords" in the BacDive data source.

We need to make sure that all the remaining "mappings" that still exist in the custom curies YAML file are removed without the loss on any information in the KGX transformation output files, and the file deleted altogether. Once the YAML file has been removed we need to make sure that the code in the transformation pipelines (ex. BacDive, BactoTraits, Madin et al) that leverage that file is also removed.