Change clicking on summary links to use XPath
Change clicking on summary links to use XPath

Based on local testing this speeds up this step by around 10% on the
[admin manager features](https://github.com/alphagov/digitalmarketplace-functional-tests/blob/main/features/admin/manage_admin_users.feature)
which are one of the slowest features to run.

https://trello.com/c/qJcotD8J/26-3-investigate-why-steps-of-the-form-and-i-click-the-summary-table-take-5-10s-or-more-and-fix

alphagov/digitalmarketplace-functional-tests,alphagov/digitalmarketplace-functional-tests,alphagov/digitalmarketplace-functional-tests