LG-12294: Set maximum delay for aggregated email events

[aduth]

🎫 Ticket

Supplemental improvement for LG-12294

🛠 Summary of changes

Updates logic for aggregated email sign-in notification to prevent stale events from being included in the email.

Related Slack discussion: https://gsa-tts.slack.com/archives/C0NGESUN5/p1713191072377119?thread_ts=1712932922.568999&cid=C0NGESUN5

Examples:

• As discussed in the Slack thread above, enabling in sandbox environments and then quickly disabling to address LG-12294: Fix asynchronous email delivery for aggregated sign-in email #10421 produced stale events when re-enabling today
• As discussed in the Slack thread above, starting local development server today (Monday) prompted an email notification for sign-ins that occurred at the end of day Friday

📜 Testing Plan

Verify tests pass:

rspec spec/services/user_alerts/alert_user_about_new_device_spec.rb

Verify you don't get an email after a long delay:

1. Go to http://localhost:3000
2. Sign in with email and password (don't MFA)
3. Stop the local development server process
4. Wait 15 minutes
5. Start the local development server
6. Wait for the job to run
7. Observe that you don't receive an email notification about your sign-in

[jmdembe]

👍🏾

[kevinsmaster5]

LGTM