Remove capitalized field names in enriched indexes

[jsmanrique]

According to indexes schema there are no capitalized field names. But checking the index pattern, there are some field names both Capitalized and lowercased. It causes too much noise during data discovery phase

[fioddor]

This shows the noise at the UI: Author_bot and Author-domain are shown duplicated. These are just 2 examples. There are many more duplicated fields like these.

[fioddor]

According to @jjmerchante: this function causes the duplication. It loops over the backend-declared roles and then over the generic author. Thus, Git for instance declares a capitalized Author role and then the generic lowercased author, common to all backends, is added.