[Forwardport] Fix sending duplicate emails

[nmalevanec]

Original Pull Request

#17484

Preconditions

1. Magento 2.2.4 or 2.2.5
2. Wyomind Cron Scheduler v1.4.0

Description

We installed Wyomind Cron Scheduler v1.4.0 and in the result, we have duplicates email (5-6 emails for 1 order).
This hotfix warns against similar situations with sending duplicate emails and adds a limit of 50 emails per cronjob.

Steps to reproduce:

1. Disable crontab
2. Make 2 or more orders
3. Enable crontab

Expected result

No duplicate Emails.

Actual result

Duplicate Emails.

[magento-engcom-team]

Hi @nmalevanec. Thank you for your contribution
Here is some useful tips how you can test your changes using Magento test environment.
Add the comment under your pull request to deploy test or vanilla Magento instance:

• @magento-engcom-team give me test instance - deploy test instance based on PR changes
• @magento-engcom-team give me {$VERSION} instance - deploy vanilla Magento instance

For more details, please, review the Magento Contributor Assistant documentation

[magento-engcom-team]

Hi @nmalevanec. Thank you for your contribution.
We will aim to release these changes as part of 2.3.0.
Please check the release notes for final confirmation.