Tech Debt: entity emails should be stored in LEAR not AUTH

Currently when a registered office email address is added to a business, that email is stored in AUTH. This may have been because when we started to build the Benefit company incorporation application, we thought if there wasn't an email at the profile level, when an email was added in the IA, then we'd update the profile. This mapping to the account email was later fixed so it didn't update the account email.

Because the business email is stored in AUTH, it makes retrieving this info difficult for director search. Also more complicated for migrating entities from COLIN to postgress.

No files, tests, or entry points are named. Start by tracing how registered-office emails are written to AUTH and how LEAR, director search, and COLIN-to-Postgres migration consume them; done means the email is stored in LEAR and those retrieval and migration paths still work.

Written by the indexing model from the issue text.