fix: text style in extension point definition page (#6179)

#### What type of PR is this?

/area ui
/kind bug
/milestone 2.17.0

#### What this PR does / why we need it:

修复插件扩展点设置页面标题的颜色问题。

#### Does this PR introduce a user-facing change?

```release-note
None
```

ui/console-src/modules/system/plugins/PluginExtensionPointSettings.vue

@@ -57,7 +57,7 @@ watch(
           <div
             class="sticky top-0 z-10 flex h-12 items-center border-b bg-white px-4"
           >
-            <h2 class="font-semibold text-green-900">扩展点定义</h2>
+            <h2 class="font-semibold text-gray-900">扩展点定义</h2>
           </div>
           <ul
             class="box-border h-full w-full divide-y divide-gray-100 overflow-auto"
@@ -98,7 +98,7 @@ watch(
           <div
             class="sticky top-0 z-10 flex h-12 items-center space-x-3 border-b bg-white px-4"
           >
-            <h2 class="font-semibold text-green-900">
+            <h2 class="font-semibold text-gray-900">
               {{ selectedExtensionPointDefinition?.spec.displayName }}
             </h2>
             <small class="line-clamp-1 text-gray-600">