Fix nova evacuate issues for RBD

For RBD scenario, there are some issues in Nova code
now against evacuate function:

1. Based on current implementation, nova evacuate and
nova rebuild are sharing some code. When user enables
the on_shared_storage option for nova evacuate, nova
will check if the instance path is accessible. For
the RBD scenario, the volume(block) is shared between
different hosts, though the path isn't shared at the
filesystem level. This patch fixes this issue and adds
test cases for that.

2. Missing the 'recreate' parameter for rebuild method.
Though the libvirt driver doesn't implement rebuild
method(only Ironic driver implements it), but we really
need to set 'recreate' in kwargs so it gets passed to
_rebuild_default_impl so we don't call driver.destroy
on evacuate for shared filesystem/block storage cases.
It is fixed in this patch and test case is added as well.

Closes-Bug: 1249319
Closes-Bug: 1340411

Change-Id: Idc8c45b055e986cf85730235d5d25777632ad1c1
Merge "Fix nova evacuate issues for RBD"