fix performance issue with item rarity outlines

[IlmarsXd]

Uses a single drop-shadow call for the outline.
The performance issue comes from the tooltip rendering causing the full page re-render and therefore reapplies the dropshadow

[FrutyX]

Performance issue? What issue? Modern computers are only getting faster, not slower.

This change is very unnecessary.

[IlmarsXd]

Even on good systems, some people (including me) have seen problems with performance due to the outlines.
It might be something specific to the browser, or some settings since comparing similar systems also didnt show the same results.
This still is more efficient and has no downsides

[FrutyX]

You could also turn off item shadows in the settings completely, however, I do not have these performance issues, so I'll just let someone else (Thanos for example) to be the judge of this.

The culprit, like you said, could be somewhere else tho.