LUInstanceCreate: Run rename script on instance import

If an instance is imported with a different name, network settings may have to
be changed. Since import scripts may not already to the right thing, we decided
to run the rename script. The same technique is already used for inter-cluster
instance moves.

Signed-off-by: Michael Hanselmann <hansmi@google.com>
Reviewed-by: Iustin Pop <iustin@google.com>