As of #10393 some icons in the chat were invisible, looking at the icons
I noticed that the viewport was actually 800x800, I scaled that down to
16x16 and now they work fine again.

Also remove the `reply_arrow_left` icon because it is not used at all.

Thanks to @RemcoSmitsDev for noticing.

I don't have any expertise in svg's, so if something is off about the
svg markup reach out to me.

Release Notes:

- N/A