Send account validation email when pipeline fails

What does this MR do and why?

This MR is part of #346233 (closed).

It implements sending of Account Validation email (introduced in !75080 (merged)) when a pipeline fails due to an unverified account (of the pipeline creator).

Why are we sending this email?

We want to check if sending this email increases initial verify usage (see #346233 (closed)).

Note: tracking will be implemented in a separate MR.

Screenshots or screen recordings

1. Create a project
   GIF

   
2. Start a pipeline by adding a .gitlab-ci.yml to the project
   GIF

   
3. Pipeline fails because user's account is not verified
   GIF

   
4. Account Validation email is sent
   GIF

   

How to set up and validate locally

Set up

1. Ensure your GDK instance is EE (you might have to upload a License)

2. Ensure the following feature flags are enabled:

   1. account_validation_email
   2. ci_require_credit_card_on_trial_plan

   # In Rails console (run `bin/rails c` in `/path/to/gitlab-development-kit/gitlab`)
   > Feature.enable(:account_validation_email)
   > Feature.enable(:ci_require_credit_card_on_trial_plan)

3. Create a test user and group

   # In Rails console
   > user = FactoryBot.create(:user, username: 'user_dec1_1', email: 'user_dec1_1@example.org', password: '12345678')
   # Create a new Group & assign the new user as its owner
   > group = FactoryBot.create(:group)
   > group.add_owner(user)

4. Create a trial subscription for the group

   # In Rails console
   # Turn on billing features in the app
   > ApplicationSetting.first.update(check_namespace_plan: true)
   # Find or create the Ultimate plan
   > plan = Plan.create_with(title: 'Ultimate (Formerly Gold)').find_or_create_by(name: :ultimate)
   # Create a new trial subscription for the Group
   > GitlabSubscription.create(namespace: group, hosted_plan: plan, seats: 10, start_date: Date.current, end_date: Date.current.advance(years: 1), trial: true, trial_starts_on: Date.current, trial_ends_on: Date.current.advance(days: 30))

5. Ensure that your test user is opted-in to receive marketing emails Go to http://localhost:3000/-/profile/notifications and check Receive product marketing emails checkbox

   Screenshot

   

Validate

1. Login with your test user

2. Navigate to the test group

   Group with trial subscription

   

3. Create a project

4. Add a .gitlab-ci.yml to the project to start a pipeline

   GIF

   

5. Validate that the pipeline for the commit fails with the reason Pipeline failed due to the user not being verified

   Screenshot

   

6. Go to letter opener (http://127.0.0.1:3000/rails/letter_opener/) and validate that the email has been sent

   Screenshot of the email you should have received

   

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.