Refactor vulnerability report image filter tooltip into image filter

What does this MR do and why?

On the vulnerability report, there's an image filter that truncates its dropdown items and shows a tooltip:

Previously, the truncation was added to FilterItem, a common component used by all the filters for their dropdown items. Because the image filter is the only filter that needs this truncation and tooltip, it's better to move it into the image filter itself, rather than having it in FilterItem and only ever have one filter use it.

MR acceptance checklist

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Related to #382346 (closed)