Adjust language in publication results email

[jazairi]

Why these changes are being introduced:

The publication results email lists theses that were "sent to preservation." This language is inaccurate; the theses are queued for preservation at this point, and may not be sent to the Archivematica bucket if the preservation job fails.

Relevant ticket(s):

https://mitlibraries.atlassian.net/browse/ETD-645

How this addresses that need:

This changes the language to "Total theses queued for preservation."

Side effects of this change:

This does nothing to confirm or report on which theses were actually sent to preservation. (ETD-646 will evaluate the best way to do this.)

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: 98.311%. remained the same
when pulling abf8228 on etd-645-publication-results-email
into af23f2e on main.