test: extend timeout for ‘get leader schedule’ test (#1201)

## Summary
This test seems to timeout a lot in CI these days. Let's try extending the timeout.

## Test Plan
```shell
pnpm test:live-with-test-validator
```

Author: steveluscher

packages/library-legacy/test/connection.test.ts

@@ -939,7 +939,7 @@ describe('Connection', function () {
       expect(Array.isArray(slots)).to.be.true;
       expect(slots.length).to.be.at.least(4);
     }
-  });
+  }).timeout(30 * 1000);
 
   it('get slot', async () => {
     await mockRpcResponse({