Update system note icon design

Unfortunately the design of the new system note icons was using an outdated mockup so the wrong version was implemented. We need to update the design to match the most recent mockups.

cc @hazelyang

added ~874211 label

@victorwu Can we include this improvement for 9.2?

assigned to @annabeldunstone

I'll work on having this finished today so maybe it can be part of 9.1.

changed milestone to %9.1

Awesome, thanks @annabeldunstone !

@annabeldunstone : Labeling this as regression since you said you want it be part of 9.1. Let me know if that's incorrect.

added regression label

mentioned in merge request !10667 (merged)

closed via merge request !10667 (merged)

mentioned in commit e802a881

I remembered there was a reason we changed the system note icons not to be indented, but I can't find where it is now...

@annabeldunstone @tauriedavis @victorwu Thank you for creating this issue and changing the layout again. This version looks good!

mentioned in commit 58e53a01