Make the KCard thumbnail handle large Card width

[AllanOXDi]

Desired behavior

The thumbnail should maintain its height at all KCard widths.

Current behavior

It appears that the larger the KCard when set to horizontal layout and thumbnailDisplay small, the thumbnail height goes past the KCard itself, thus overshadowing the footer section.

[MisRob]

Thanks for reporting @AllanOXDi :) I can't say for sure right now, but it's quite possible that this will be resolved by #748 - so when we start building actual features in Studio (that will need to happen with KGrid), let's see if it can still be reproduced.