[Backport 2.1-develop] #11586 Fix duplicated crontab 2>&1 expression

[adrian-martinez-interactiv4]

Description

Installing or removing crontab via command adds 2>&1 repeatedly, even for crontab entries not related with Magento, if they match a regular expression. See details in #11586.

Fixed Issues (if relevant)

1. Cron install / remove via command messes up stderr 2>&1 entries #11586: Cron install / remove via command messes up stderr 2>&1 entries

Manual testing scenarios

As explained in #11586

Contribution checklist

• Pull request has a meaningful description of its purpose
• All commits are accompanied by meaningful commit messages
• All new or changed code is covered with unit/integration tests (if applicable)
• All automated tests passed successfully (all builds on Travis CI are green)

[orlangur]

Hi @adrian-martinez-interactiv4, a small note on copyright header - it should be consistent across all files in corresponding version, so, for 2.1.x there should still be year. It is enforced by tests running internally on Bamboo.

No action required from your side, I was wondering how GitHub UI editing looks like in action :)

[adrian-martinez-interactiv4]

@orlangur I saw you changed that, and I realized I should have respected the headers :D