[JDBC] Implement DataSource login timeout

从 ArrowFlightJdbcDataSource.setLoginTimeout(int)、getLoginTimeout() 和 DataSource.getConnection() 路径开始；将它们与现有的 connectTimeoutMs 行为进行比较。为默认值、setter/getter、超时强制执行、SQLTimeoutException 以及部分创建资源的清理添加覆盖。完成的标准是，0 保留默认行为，非零登录超时会取消失败的尝试且不会发生泄漏。

Describe the enhancement requested

ArrowFlightJdbcDataSource.setLoginTimeout(int) currently throws SQLFeatureNotSupportedException, and getLoginTimeout() always returns 0.

Implement the JDBC DataSource login-timeout contract:

• Store and return the timeout configured for each ArrowFlightJdbcDataSource instance.
• Apply a nonzero timeout to connection establishment through DataSource.getConnection().
• Preserve the JDBC semantics of zero: use the default system timeout if one exists; otherwise, do not impose a timeout.
• 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 for the default value, setter/getter behavior, timeout enforcement, exception type, and resource cleanup.

This is distinct from #494/#495. The existing connectTimeoutMs property configures Netty socket connection attempts; the JDBC login timeout applies to the overall database connection attempt exposed by DataSource.getConnection().

Context: #1027 and the follow-up discussion.

Related DriverManager work: https://github.com/apache/arrow-java/issues/1268