Revert and optimize database migration and email handling processes

[tjementum]

Summary & Motivation

Revert "Simplify retry logic for handling when SQL Server is still starting on localhost". In a previous pull request, a different DB context execution strategy was introduced to simplify code that handles errors during database migrations locally while SQL Server was still starting. This change caused migrations to fail in Azure.

Revert "Stop background workers after they have run database migrations". In an earlier pull request, background workers running database migrations were made to stop in hopes of allowing Azure container apps to scale to 0. However, this caused the servers to crash and continuously restart.

Change mail sending in Azure to return when mail is initiated instead of waiting for delivery. Previously, sending mail using Azure Communication Services had WaitUntil.Completed, causing up to a 10-second delay in the UI during sign-up. This is now changed to WaitUntil.Started for faster response.

Checklist

• [x] I have added a Label to the pull-request
• [x] I have added tests, and done manual regression tests
• [x] I have updated the documentation, if necessary

[sonarcloud[bot]]

Quality Gate passed

Issues
2 New issues
0 Accepted issues

Measures
0 Security Hotspots
0.0% Coverage on New Code
0.0% Duplication on New Code

See analysis details on SonarCloud