[Backport]Magento should create log if an observer not implement ObserverInterface

[Nazar65]

Description (*)

In developer mode, if an observer does not implement ObserverInterface, Magento throws an exception. This is the expected behavior.

What I don't understand is that it does not do anything for other deploy modes (default and production). It silently discards the observer without even putting an entry to logs.

Original PR #21767

Fixed Issues (if relevant)

1. Magento should create a log entry if an observer does not implement ObserverInterface #21755: Magento should create a log entry if an observer does not implement ObserverInterface

Manual testing scenarios (*)

1. Create an Observer class wich not implements ObserverInterface
2. Check Log sytem.log

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)

[m2-assistant]

Hi @Nazar65. Thank you for your contribution
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[magento-engcom-team]

Hi @orlangur, thank you for the review.
ENGCOM-4714 has been created to process this Pull Request

[soleksii]

✔️ QA Passed

[m2-assistant]

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