Add "runtime GC" reaction for `@managed` properties

[jskupsik]

… model fields

Hoist P/R Checklist

Pull request authors: Review and check off the below. Items that do not apply can also be checked off to indicate they have been considered. If unclear if a step is relevant, please leave unchecked and note in comments.

• [ ] Caught up with develop branch as of last change.
• [ ] Added CHANGELOG entry, or determined not required.
• [ ] Reviewed for breaking changes, added breaking-change label + CHANGELOG if so.
• [ ] Updated doc comments / prop-types, or determined not required.
• [ ] Reviewed and tested on Mobile, or determined not required.
• [ ] Created Toolbox branch / PR, or determined not required.

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