update confirmation email test to use SES rather than notify

[alice-carr]

What problem does this pull request solve?

we are switching from using notify to send confirmation emails to using SES - this will keep it in line with the copy of answers feature.

This pr updates the end to end tests so that they now check s3 rather than notify for the confirmation email. This includes adding a new confirmation email that has already been set up in ses.

Trello card: https://trello.com/c/GfBTJbNL/3154-use-ses-to-send-all-confirmation-emails

Things to consider when reviewing

you can review this by running the e2e tests against the forms-runner branch: use-ses-to-send-all-confirmation-emails

• Ensure that you consider the wider context.
• Does it work when run on your machine?
• Is it clear what the code is doing?
• Do the commit messages explain why the changes were made?
• Has all relevant documentation been updated?