Update progress bar background color to use button background variable

Author: robertpiosik

packages/ui/src/components/editor/panel/ContextUtilisation/ContextUtilisation.module.scss

@@ -21,7 +21,7 @@
 
   &__progress {
     height: 100%;
-    background-color: var(--vscode-focusBorder);
+    background-color: var(--vscode-button-background);
     border-top-right-radius: 999px;
     border-bottom-right-radius: 999px;