[Bug]: Deeplinks - Sell doesn't redirect to MetaMask but just opens Portfolio

### Describe the bug

Sell doesn't redirect to MetaMask but just opens Portfolio

### Expected behavior

It should open MM sell page, according to this PR: https://github.com/MetaMask/metamask-extension/pull/40231

### Screenshots/Recordings

https://github.com/user-attachments/assets/92a406f1-48a9-475d-96b2-e7e75c367c1d

### Steps to reproduce

1. Open https://link.metamask.io/sell?chainId=59144&address=0x176211869cA2b568f2A7D4EE941E073a821EE1ff&amount=25
2. You should be redirected to the sell page, with USDC on Linea selected. Amount is currently not correctly consumed by MMPortfolio => fix needed there

### Error messages or log output

```shell

```

### Where was this bug found?

Internal release testing

### Version

13.21.0

### Build type

None

### Browser

Chrome

### Operating system

MacOS

### Hardware wallet

_No response_

### Additional context

_No response_

### Severity

_No response_

Start with the deeplink flow for https://link.metamask.io/sell and compare its behavior with the expected flow described in PR #40231. Check how the link reaches MMPortfolio and how the sell-page destination and amount are consumed. Done means the link opens the MetaMask sell page with USDC on Linea selected and the amount handled correctly.

Written by the indexing model from the issue text.