Setup SMS for Sri Lanka H1'25 (#5504)

**Story card:** [sc-14154]

## Because

The current SMS notifications for SL expires this month. We need to
setup more notifications through H1 next year.

## This addresses

Setting up SMS notifications for SL

## Test instructions

n/a

Author: igbanam

db/migrate/20241204155510_setup_sms_reminder_sri_lanka_2025_jan_june.rb

@@ -0,0 +1,37 @@
+# frozen_string_literal: true
+
+class SetupSmsReminderSriLanka2025JanJune < ActiveRecord::Migration[6.1]
+  PATIENTS_PER_DAY = 5000
+  EXPERIMENTS_DATA = %w[Jan Feb Mar Apr May Jun].map do |month|
+    {
+      start_time: "#{month} 2025".to_datetime.beginning_of_month,
+      end_time: "#{month} 2025".to_datetime.end_of_month,
+      current_patients_experiment_name: "Current Patient #{month} 2025"
+    }
+  end
+
+  def up
+    return unless CountryConfig.current_country?("Sri Lanka") && SimpleServer.env.production?
+
+    EXPERIMENTS_DATA.each do |experiment_data|
+      ActiveRecord::Base.transaction do
+        Experimentation::Experiment.current_patients.create!(
+          name: experiment_data[:current_patients_experiment_name],
+          start_time: experiment_data[:start_time],
+          end_time: experiment_data[:end_time],
+          max_patients_per_day: PATIENTS_PER_DAY
+        ).tap do |experiment|
+          cascade = experiment.treatment_groups.create!(description: "sms_reminders_cascade - #{experiment_data[:current_patients_experiment_name]}")
+          cascade.reminder_templates.create!(message: "notifications.sri_lanka.one_day_before_appointment", remind_on_in_days: -1)
+          cascade.reminder_templates.create!(message: "notifications.sri_lanka.three_days_missed_appointment", remind_on_in_days: 3)
+        end
+      end
+    end
+  end
+
+  def down
+    EXPERIMENTS_DATA.map do |experiment_data|
+      Experimentation::Experiment.current_patients.find_by_name(experiment_data[:current_patients_experiment_name])&.cancel
+    end
+  end
+end

db/structure.sql

@@ -7857,6 +7857,7 @@ INSERT INTO "schema_migrations" (version) VALUES
 ('20241125153335'),
 ('20241125155649'),
 ('20241126111757'),
-('20241129212725');
+('20241129212725'),
+('20241204155510');