Refactors test setup and teardown logic to use `t.Cleanup` instead
of `defer`. This ensures that cleanup functions are correctly scoped
to each subtest's lifecycle, improving test isolation and reliability.
The `setUpNetlinkTest` helper function is also improved to correctly
save and restore the original network namespace, ensuring that tests
do not leak state.
To support this, a `Close()` method that returns an error is added to
the `Handle` struct, allowing for proper cleanup of underlying netlink
sockets. The test helpers are updated to use this new method,
preventing resource leaks between tests.
Additionally, a bug in the `netns` tests is fixed where a large
namespace ID could overflow a 32-bit integer, causing spurious
failures on some systems.
This patch implements both tc and filter chains.
We also need to align tc filter delition implementation
with iprote2 to delete filters withichain by passing
additional bits during filter deletion call.
