perf(sidebar): eliminate unnecessary re-renders in workspace switcher for non-search users

- onMouseEnter: only set highlightedIndex when showSearch is true, preventing
  a state update + re-render on every workspace row hover for users with ≤ 3
  workspaces where the search is never shown
- onOpenChange: only reset workspaceSearch and highlightedIndex when showSearch
  is true, since both values are always already at their defaults for non-search
  users and setting them triggers a pointless re-render during dropdown close
- data-workspace-row-idx: only set when showSearch is true since the scroll
  effect that reads this attribute is already gated on showSearch

Author: waleedlatif1

apps/sim/app/workspace/[workspaceId]/w/components/sidebar/components/workspace-header/workspace-header.tsx

@@ -355,7 +355,7 @@ function WorkspaceHeaderImpl({
             if (open && showSearch) {
               requestAnimationFrame(() => searchInputRef.current?.focus())
             }
-            if (!open) {
+            if (!open && showSearch) {
               setWorkspaceSearch('')
               setHighlightedIndex(0)
             }
@@ -479,8 +479,8 @@ function WorkspaceHeaderImpl({
                     return (
                       <div
                         key={workspace.id}
-                        data-workspace-row-idx={idx}
-                        onMouseEnter={() => setHighlightedIndex(idx)}
+                        data-workspace-row-idx={showSearch ? idx : undefined}
+                        onMouseEnter={showSearch ? () => setHighlightedIndex(idx) : undefined}
                       >
                         {editingWorkspaceId === workspace.id ? (
                           <div