Remove ProQuest consent field from receipt email

[jazairi]

Why these changes are being introduced:

We removed the ProQuest consent field from the thesis submission form, but forgot to remove the field from the mailer. Thus, when a grad student submits their thesis, they see this nonexistent field in their confirmation email.

Relevant ticket(s):

N/A

How this addresses that need:

This removes the field from the mailer.

Side effects of this change:

None.

Developer

• All new ENV is documented in README
• All new ENV has been added to Heroku Pipeline, Staging and Prod
• ANDI or Wave has been run in accordance to
  our guide and
  all issues introduced by these changes have been resolved or opened as new
  issues (link to those issues in the Pull Request details above)
• Stakeholder approval has been confirmed (or is not needed)

Code Reviewer

• The commit message is clear and follows our guidelines
  (not just this pull request message)
• There are appropriate tests covering any new functionality
• The documentation has been updated or is unnecessary
• The changes have been verified
• New dependencies are appropriate or there were no changes

Requires database migrations?

NO

Includes new or updated dependencies?

NO

[coveralls]

coverage: 98.313%. remained the same
when pulling 095f158 on remove-proquest-from-email
into 679165e on main.

[matt-bernhardt]

I see the tests passing, and I see the updated test is the same format used to confirm that undergraduates aren't seeing the (now-removed) message - so this seems fine for me.

I have not confirmed the mailer itself locally, but the change to the template seems straightforward enough to be reviewable without it. The sentence we want to be removed is just gone.