Trials cannot be created by users only one name

Summary

In the new trial flow introduced in 64e457e8 a user with only "first name" in the "Name" field is unable to create a trial.

Steps to reproduce

  1. Create a user with only one name, or modify an existing user to remove any last name(s)
  2. Attempt to initiate a trial
  3. Observe the error message "Last name cannot be blank", but no last name field is present on the form.

What is the current bug behavior?

A user with only one name cannot initiate a trial and isn't directed anywhere where they can add a last name to create a trial.

What is the expected correct behavior?

We should either handle this transparently by noting nil entries for last name, or add a "last name" field in the trial form so a user experiencing this can add a last name.

Relevant logs and/or screenshots

image

Output of checks

This bug happens on GitLab.com

Results of GitLab environment info

GitLab Enterprise Edition 12.5.0-pre 9e0448ab

Workarounds

Users experiencing this error can add a last name from https://gitlab.com/profile

If they don't have a last name, a space followed by any string will work.

/cc @jeromezng @s_awezec