Migrate epic events to internal events: vol.3 - date events

What does this MR do and why?

Related to #421593 (closed)

Migrate some of the redis_hll_counters.epics_usage.epics_usage_total_unique_counts_monthly event's sub-events to Internal Events API.

Script used to update the files:

class DebugGenerator < Gitlab::Analytics::InternalEventsGenerator
  source_root File.expand_path('generator_templates/gitlab_internal_events', __dir__)

  def create_metric_file
    validate!

    template "event_definition.yml",
      event_file_path(event),
      options.fetch(:event_desc)
  end

  def milestone
    "16.5"
  end
end

is_ee = true
mr_number = 131896
unique_by = "user.id"
section = "dev"
stage = "plan"
group = "product_planning"
events_with_desc = [
['g_project_management_users_setting_epic_start_date_as_fixed', "An epic's start date has been set as fixed"],
['g_project_management_users_setting_epic_start_date_as_inherited', "An epic's start date has been set as inherited"],
['g_project_management_users_setting_epic_due_date_as_fixed', "An epic's due date has been set as fixed"],
['g_project_management_users_setting_epic_due_date_as_inherited', "An epic's due date has been set as inherited"],
['g_project_management_users_updating_fixed_epic_start_date', "An epic's fixed start date has been updated"],
['g_project_management_users_updating_fixed_epic_due_date', "An epic's fixed due date has been updated"],
]


events_with_desc.each do |event_name, event_desc|
  tiers = %w[premium ultimate]
  tiers = %w[free premium ultimate] if !is_ee
  DebugGenerator.new([], {
    event: event_name,
    event_desc: event_desc,
    section: section,
    stage: stage,
    group: group,
    mr: "https://gitlab.com/gitlab-org/gitlab/-/merge_requests/#{mr_number}",
    unique: unique_by,
    tiers: tiers
  }).invoke_all
  ['28d', '7d'].each do |days|
    dir_prefix = is_ee ? "ee/" : ""
    event_file_pattern = event_name.delete_prefix('g_project_management_')
    files = Dir["#{dir_prefix}config/metrics/counts_#{days}/*\_#{event_file_pattern}\_*"]
    raise StandardError, "Multiple files found: #{files}" unless files.count == 1
    file_name = files.first

    text = File.read(file_name)
    new_contents = text.gsub(/distribution:/, "events:
  - name: #{event_name}
    unique: #{unique_by}\ndistribution:")
    new_contents = new_contents.gsub(/data_source: redis_hll/, "data_source: internal_events")

    File.open(file_name, "w") {|file| file.puts new_contents }
  end
end

Screenshots or screen recordings

How to set up and validate locally

1. Set up snowplow-micro
2. Trigger the events migrated here:
   • set a fixed date for an epic's start date or due date
   • update any of those dates
   • inherit any of them from a milestone
3. Make sure that the events have been triggered with content as per their new event definition files [eg. - category sent as InternalEventTracking] on the http://localhost:9091/micro/good snowplow micro endpoint.

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.