Upgrade @metamask/token-search-discovery-controller to version 4.0.0

A new major version of `@metamask/token-search-discovery-controller`, 4.0.0, is now available. This issue has been assigned to you and your team because you code-own this package in the `core` repo. If this package is present in this project, please prioritize upgrading it soon to unblock new features and bugfixes.

No file or test is named. Search the metamask-mobile package manifests for @metamask/token-search-discovery-controller, confirm whether it is present, and inspect the dependency's 4.0.0 release changes before upgrading. Done means the project uses version 4.0.0 and its existing checks pass.

Written by the indexing model from the issue text.