test_integration.tasks: Do not fail cleanup if backup directory does not exist

If the test backup directory was never created (for example if
there was an early failure, or install was never run),
we don't want the test to fail.
Do not restore if the backup dir is not there.

Reviewed-By: Martin Kosek <mkosek@redhat.com>
ipatests: test_trust: Change expected home directories for posix users

Information from the AD about the home directories is not leveraged at
all, but is generated from the username and domain. Fix the assumptions
in the tests.

Also changes 'Subdomain Test User' to 'Subdomaintest User' to be more
consistent.

https://fedorahosted.org/freeipa/ticket/4184

Reviewed-By: Jakub Hrozek <jhrozek@redhat.com>
Reviewed-By: Alexander Bokovoy <abokovoy@redhat.com>