[JDBC] Honor DriverManager login timeout

### Describe the enhancement requested

`ArrowFlightJdbcDriver.connect()` does not currently honor the timeout configured through `DriverManager.setLoginTimeout(int)`.

Implement support for the `DriverManager` login timeout:

- Read the value exposed by `DriverManager.getLoginTimeout()` when establishing a connection selected by `DriverManager`.
- Preserve the JDBC semantics of zero: do not impose a login timeout.
- Apply a nonzero timeout to the overall connection attempt, not only the underlying Netty socket connection.
- If the timeout expires, attempt to cancel the connection attempt and throw `SQLTimeoutException`.
- Clean up any allocator, channel, or partially constructed client when the attempt is cancelled or times out.
- Add tests that set and restore the global `DriverManager` timeout and verify timeout enforcement, exception type, and resource cleanup.

This is distinct from #494/#495. The existing `connectTimeoutMs` property configures Netty socket connection attempts and does not consume the timeout configured through `DriverManager`.

Context: #1027 and [the follow-up discussion](https://github.com/apache/arrow-java/pull/1027#issuecomment-5447203124).

Related DataSource work: https://github.com/apache/arrow-java/issues/1267

Il punto di ingresso è ArrowFlightJdbcDriver.connect(); leggi innanzitutto il suo percorso di connessione corrente e la gestione esistente di connectTimeoutMs. Aggiungi test che impostino e ripristinino il timeout globale di DriverManager, verifichino il comportamento con timeout pari a zero e diverso da zero, SQLTimeoutException e la pulizia di allocator, channel e client quando il tentativo complessivo viene annullato o va in timeout.

Scritto dal modello di indicizzazione a partire dal testo della issue.