fix(sidebar): Remove fixed scrollbar at short screen sizes (#60636)

Removed some extra CSS that was forcing a scrollbar to be visible in the
sidebar.
This CSS was only applied when the window is short, but wide, which
seems weird to me; like a leftover from something else.

Anyway, having this scrollbar in there meant that the "User Feedback"
label needs to get truncated, but the behavior was really weird to
watch. So lets remove the excess.


| Before | After |
| --- | --- |
| <img width="611" alt="before"
src="https://github.com/getsentry/sentry/assets/187460/c67ad2eb-1b90-424f-a410-b488a0101a9b">
| <img width="610" alt="after"
src="https://github.com/getsentry/sentry/assets/187460/81f59463-c872-432a-b11b-04c4be3e0d5e">
|

static/app/components/sidebar/index.tsx

@@ -693,14 +693,6 @@ const PrimaryItems = styled('div')`
     border-bottom: 1px solid ${p => p.theme.gray400};
     padding-bottom: ${space(1)};
     box-shadow: rgba(0, 0, 0, 0.15) 0px -10px 10px inset;
-    &::-webkit-scrollbar {
-      background-color: transparent;
-      width: 8px;
-    }
-    &::-webkit-scrollbar-thumb {
-      background: ${p => p.theme.gray400};
-      border-radius: 8px;
-    }
   }
   @media (max-width: ${p => p.theme.breakpoints.medium}) {
     overflow-y: visible;