Stat panel is only scrollable if needed (#90341)

## About The Pull Request

I was not aware of https://github.com/tgstation/tgstation/pull/90278
adding ``scrollable`` to Experiscanner, so I was looking at a fix to
that and found out that it's caused by ``overflow-y`` not working in its
scss panel. The linked PR failed to address that, so clients on 515 now
have 2 scrolls on it, this fixes that.
I checked every other instance to see which other ones might've been
broken, and while none were non-functional, I found the TaychonArray
scss file was completely unused, we replaced it in changes to the
Taychon Array machine itself and related UI changes, so I'm deleting it.
Lastly, I'm making the stat panel use ``auto`` instead of always showing
the scrollbar, because I thought it looked nicer.

## Why It's Good For The Game

Removes double scrollbar for 515 users and makes stat panel not always
have a scrollwheel when it can't even be used.

## Changelog

🆑
fix: Users on 515 no longer have 2 scrollwheels on the experiscanner.
del: The stat panel only shows the scrollwheel when there's something to
scroll to.
/🆑

html/statbrowser.css

@@ -112,7 +112,7 @@ img {
 #statcontent {
 	flex: 1;
 	padding: 0.75em 0.5em;
-	overflow-y: scroll;
+	overflow-y: auto;
 	overflow-x: hidden;
 }
 

tgui/packages/tgui/styles/interfaces/ExperimentConfigure.scss

@@ -64,7 +64,6 @@
 
 .ExperimentConfigure__ExperimentsContainer > :last-child {
   flex: 1;
-  overflow-y: auto;
 }
 
 // Required for the time being otherwise we'll end up coloring the tooltip

tgui/packages/tgui/styles/interfaces/TachyonArray.scss

@@ -1,13 +0,0 @@
-.TachyonArray__ActiveRecord {
-  margin: 0 0.5em 0 0.8em;
-}
-
-.TachyonArray__Content {
-  overflow-x: hidden;
-  overflow-y: auto;
-}
-
-.TachyonArray__ResearchFooter > * {
-  width: 100%;
-  text-align: center;
-}

tgui/packages/tgui/styles/main.scss

@@ -48,7 +48,6 @@
 @include meta.load-css('./interfaces/RequestManager.scss');
 @include meta.load-css('./interfaces/Roulette.scss');
 @include meta.load-css('./interfaces/Safe.scss');
-@include meta.load-css('./interfaces/TachyonArray.scss');
 @include meta.load-css('./interfaces/Techweb.scss');
 @include meta.load-css('./interfaces/Trophycase.scss');
 @include meta.load-css('./interfaces/Uplink.scss');