Pass trial parameters when importing group

What does this MR do and why?

When customer sign up with trial on the create/import project page we pass trial parameter for group creation and trial is started for that group. However if we import group, we skip these parameters. I tested in production and we can start trial for a group with imported projects. So filling the gap for the import project page.

How to set up and validate locally

bin/rails c

Feature.disable(:ensure_onboarding)

• Setup gdk to simulate SaaS - https://docs.gitlab.com/ee/development/ee_features.html#simulate-a-saas-instance and restart GDK
• Sign out. Register new user.
• On the welcome page select Just me and Create a new project.
• Submit the form.
• On the group creation page add ?trial_onboarding_flow=true to the url.
• Select Import tab. Enter group name. Click GitHub:

• In the incognito tab sign in as root. Visit /admin/sidekiq/retries.
• Wait couple minutes.
• Make sure there is GitlabSubscriptions::Trials::ApplyTrialWorker failed job.
• Make sure that job has gitlab_com_trial, sync_to_gl and namespace name arguments:

MR acceptance checklist

This checklist encourages us to confirm any changes have been analyzed to reduce risks in quality, performance, reliability, security, and maintainability.

• I have evaluated the MR acceptance checklist for this MR.

Related to #411443 (closed)