Import doesn't check if event creation dates matches the issue creation date

Summary

Manually modifying the event creation date for an issue works without any checks on the actual issue created_at.

Steps to reproduce

1. Export a sample project
2. Edit the project.json and change the created_at date for the event of an issue (or, MR, would work for all event types)
3. Import the project and notice the inconsistency

Example Project

2020-01-12_00-50-424_root_test_export.tar.gz

https://gitlab.com/cat/repro-import-events

cat/repro-import-events#1 is opened 2 days ago, but the event in activity says it was opened on 01/01 (like edited in the project.json)

What is the current bug behavior?

The issue is created with a different created_at date than the event of issue creation.

What is the expected correct behavior?

The issue and event for creating the issue have consistent dates.

Possible fixes