IconButton has 2 extra pixels because of the border

[rndD]

<IconButton> size xs should be 16x16 by design.

We can:

• make border optional
• remove border (why do we have it in the first place??
• make icon smaller accordingly

[rndD]

cc @crisalbu @ariser

[rndD]

Blocks https://github.com/ClickHouse/control-plane/issues/13642

[ariser]

The border is requried for e.g. danger type, it's visible in this case
if we remove it, we need to replace it with box-shadow or perhaps outline, which don't take space
probably easier to keep it

[crisalbu]

It appears that we just need to reduce the padding by 1px - that should fix it.