Parse.Cloud.beforeLogin does not fire when a user is signed up and logged in for the first time

New Issue Checklist

• I am not disclosing a vulnerability.
• I am not just asking a question.
• I have searched through existing issues.
• I can reproduce the issue with the latest version of Parse Server.

Issue Description

beforeLogin trigger does not fire on signup.

Steps to reproduce

Create a beforeLogin trigger, and inside of it, a console.log, then use Parse.User.signUp() to create a new user (thus automatically logging them in)

Actual Outcome

The trigger is not called; the log is never printed to the console.

Expected Outcome

The trigger is called, because signUp not only creates the user. It also creates a session and logs them in.

Environment

4.5.0

Server

• Parse Server version: 4.5.0
• Operating system: Unknown
• Local or remote host (AWS, Azure, Google Cloud, Heroku, Digital Ocean, etc): Back4app
• Database System (MongoDB or Postgres): MongoDB
• Database version: 3.6
• Local or remote host (MongoDB Atlas, mLab, AWS, Azure, Google Cloud, etc): Back4app

Client

• SDK (iOS, Android, JavaScript, PHP, Unity, etc): JavaScript
• SDK version: 3.4.4

Start by tracing the Parse.User.signUp flow and the beforeLogin trigger entry point to determine where the first-login path diverges. Reproduce the issue with a trigger that logs its invocation, then add coverage for signup-created sessions and verify that the trigger fires as expected.