Remove "What would you like to do?" question from Welcome screen of trial registration flow

Overview

With https://gitlab.com/groups/gitlab-org/-/epics/6630 we added a question to the registration flow that allows a user to indicate if they are joining vs. setting up a project. Those that select "joining" bypass the group and project creation steps of the flow.

The page is shared with the trial flow, however, and we do not bypass any steps in that flow because to have a trial they must fill out the form and create a group.

We should remove the question from the trial-specific flow to reduce the fields and potential confusion that its presence may cause.