Fix validation of image resize with and height to calculate the target

[npomaroli]

values before checking limits

Abstract

When checking that the resized image is within the allowed limits, the width/height has to be calculated before (in cases, where at least one value is set to "auto" or not set at all).

Checklist

General

• Added abstract that describes the change
• Added changelog entry to /CHANGELOG.adoc
• Ensured that the change is covered by tests
• Ensured that the change is documented in the docs

On API Changes

• Checked if the changes are breaking or not
• Added GraphQL API if applicable
• Added Elasticsearch mapping if applicable

[plyhun]

There are breaking changes, which make it impossible to fetch the already existing image variants. Needs refactoring.