When locking was enabled with the Consul backend and the lock not properly
released, the `terraform force-unlock <lock_id>` command would do nothing as
its implementation would exit early in that case.
It now destroys the session that created the lock and clean both the lock and
the lock-info keys.
A regression test is added to TestConsul_destroyLock() to catch the issue if it
happends again.
Closes https://github.com/hashicorp/terraform/issues/22174
11eb88753d