refactor: optimize axios interceptor text/html content type detection (#7142)

#### What type of PR is this?

/area ui
/kind improvement
/milestone 2.20.x

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

Optimize axios interceptor text/html content type detection

<img width="1461" alt="image" src="https://github.com/user-attachments/assets/6bb59a1d-81cc-4ea2-ac61-17e30eab4281" />

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

```release-note
None
```

ui/src/setup/setupApiClient.ts

@@ -72,7 +72,7 @@ export function setupApiClient() {
 
       const contentType = error.response?.headers["content-type"];
 
-      if (contentType === "text/html") {
+      if (contentType.toLowerCase().includes("text/html")) {
         createHTMLContentModal({
           uniqueId: objectHash(error.response?.data || ""),
           title: error.response?.status.toString(),