fix(agent-builder): mark decorative icon aria-hidden in AttachmentGroupPill

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

Author: jonwalstedt

x-pack/platform/plugins/shared/agent_builder/public/application/components/conversations/conversation_input/attachment_group_pill.tsx

@@ -70,7 +70,7 @@ export const AttachmentGroupPill: React.FC<AttachmentGroupPillProps> = ({ group,
       <EuiFlexGroup alignItems="center" gutterSize="s" responsive={false}>
         <EuiFlexItem grow={false}>
           <div className={iconContainerStyles}>
-            <EuiIcon type={DEFAULT_ICON} size="m" color="primary" />
+            <EuiIcon type={DEFAULT_ICON} size="m" color="primary" aria-hidden={true} />
           </div>
         </EuiFlexItem>
         <EuiFlexItem style={{ minWidth: 0 }}>