Edit UI - validate business contact email

- [ ] remove "Confirm email address and related functionality"
- [ ] retain current UI email validation
- [ ] update validation so errors are not shown until Save button is clicked
- [ ] ~Legal API will further verify the email address and return error if invalid~ _no work needed here_
- [ ] ~display "invalid email" error from API~ _future_
- [ ] add/update unit tests

#### Sample page:

Locate the Edit UI's current email validation and its unit tests; inspect how validation is triggered relative to the Save button. Done means removing confirmation-email functionality, preserving current validation, deferring errors until Save, and adding or updating unit tests.

Written by the indexing model from the issue text.