[Cleanup]: Redesign confirmation refactor getTitle and getDescription to getTitleAndSubtitle

**What is this about?**

In mobile redesigned confirmations, we now have getTitleAndSubtitle. In extension, we have getTitle and getDescription. I think we can update extension to use getTitleAndSubtitle to help maintain parity.

Generally, when we alternate logic from the extension to mobile, I think we should revisit and also update the logic in extension to reduce disparities between the repos.

**Stakeholder review needed before the work gets merged**

- [ ] Engineering (needed in most cases)
- [ ] Design
- [ ] Product
- [ ] QA (automation tests are required to pass before merging PRs but not all changes are covered by automation tests - please review if QA is needed beyond automation tests)
- [ ] Security
- [ ] Legal
- [ ] Marketing
- [ ] Management (please specify)
- [ ] Other (please specify)

Start by locating the extension confirmation implementations of getTitle and getDescription, then compare them with the mobile getTitleAndSubtitle behavior described in the issue. Trace the confirmation entry points and existing automation tests before changing anything. Done means the extension uses the combined title-and-subtitle approach and required stakeholder review is complete.

Written by the indexing model from the issue text.