FIX: Remove two pane split view custom style in input system package. (#2163)

Co-authored-by: Paulius Dervinis <[email protected]>

Author: xianwangunity

Packages/com.unity.inputsystem/InputSystem/Editor/UITKAssetEditor/PackageResources/InputActionsEditorStyles.uss

@@ -13,11 +13,6 @@
 
 .body-panel-container {
     min-width: 150px;
-    border-top-width: 1px;
-    border-left-color: rgb(25, 25, 25);
-    border-right-color: rgb(25, 25, 25);
-    border-top-color: rgb(25, 25, 25);
-    border-bottom-color: rgb(25, 25, 25);
     border-right-width: 0;
 }
 
@@ -194,10 +189,6 @@
     width: 190px;
 }
 
-.unity-two-pane-split-view__dragline-anchor {
-    background-color: rgb(25, 25, 25);
-}
-
 #control-scheme-usage-title {
     margin: 3px;
     -unity-font-style: bold;