Update NuttX and NuttX Apps references to releases/12.9 in workflow f… (#4148)

* Update NuttX and NuttX Apps references to releases/12.9 in workflow files
* Remove Kconfig modification step for NuttX in spec test workflow

.github/workflows/compilation_on_nuttx.yml

@@ -88,14 +88,14 @@ jobs:
         uses: actions/checkout@v4
         with:
           repository: apache/nuttx
-          ref: releases/12.6
+          ref: releases/12.9
           path: nuttx
 
       - name: Checkout NuttX Apps
         uses: actions/checkout@v4
         with:
           repository: apache/nuttx-apps
-          ref: releases/12.6
+          ref: releases/12.9
           path: apps
 
       - name: Checkout WAMR