Add glm_source and glm_content params to free trial signup experience

Summary

We're currently dropping GLM URL parameters in the new registration experience. For example, as a test I signed up for a SaaS trial from the marketing home page which includes the follow GLM parameters https://gitlab.com/-/trial_registrations/new?glm_source=about.gitlab.com&glm_content=default-saas-trial. I created a trial with the following user/namespace: user_id: 12218743 group_id: 56312717. However, my GLM data is not present in the customers_db_trial_histories table.

During testing I noticed that after landing back in the registration experience after confirming my email the GLM fields were no longer present in the URL. I believe these parameters previously followed the user through the signup experience and we captured the values when the submitted the trial form or when the trial was applied to a specific group.

Solution

We should ensure that the GLM data is being captured when a user signups for a trial.