Fix line break in engine Allowlisted Domains textarea placeholder (#4835)

## Problem solved

Short description of the bug fixed or feature added

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## PR-Codex overview
This PR updates the `placeholder` prop of the `Textarea` component in the `cors.tsx` file to use a JavaScript expression instead of a string literal.

### Detailed summary
- Changed the `placeholder` prop from a string literal (`"https://example.com\nhttp://localhost:3000"`) to a JavaScript expression (`{"https://example.com\nhttp://localhost:3000"}`) for potentially better handling of the string.

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Author: MananTank

apps/dashboard/src/components/engine/configuration/cors.tsx

@@ -63,7 +63,7 @@ export const EngineCorsConfig: React.FC<EngineCorsConfigProps> = ({
       </Flex>
 
       <Textarea
-        placeholder="https://example.com\nhttp://localhost:3000"
+        placeholder={"https://example.com\nhttp://localhost:3000"}
         rows={4}
         {...form.register("raw")}
       />