[Dashboard] Fix prepareEvent code snippet (#5052)

## Problem solved

Short description of the bug fixed or feature added

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## PR-Codex overview
This PR focuses on removing redundant lines of code related to the `preparedEvent` declaration in the `code-overview.tsx` file.

### Detailed summary
- Removed duplicate declarations of `preparedEvent` that included `contract` and `signature: "{{function}}"`.
- Streamlined the `getContractEvents` function call by eliminating unnecessary lines.

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Author: kien-ngo

apps/dashboard/src/contract-ui/tabs/code/components/code-overview.tsx

@@ -198,7 +198,6 @@ export default function Component() {
     javascript: `import { prepareEvent, getContractEvents } from "thirdweb";
 
 const preparedEvent = prepareEvent({
-  contract,
   signature: "{{function}}"
 });
 const events = await getContractEvents({
@@ -209,7 +208,6 @@ const events = await getContractEvents({
 import { useContractEvents } from "thirdweb/react";
 
 const preparedEvent = prepareEvent({
-  contract,
   signature: "{{function}}"
 });
 
@@ -223,7 +221,6 @@ export default function Component() {
 import { useContractEvents } from "thirdweb/react";
 
 const preparedEvent = prepareEvent({
-  contract,
   signature: "{{function}}"
 });