Stop testing rebuild for ironic

Currently our tests run too long and we experience constant timeouts.
Rebuild is a relatively rarely used feature, so we plan on creating
separate jobs for it. Remove rebuild testing completely with the goal
to reintroduce it as soon as we switch to an in-tree tempest plugin.

Change-Id: I16d27b6bd900186b84df7045a6e4f66257fefac4
diff --git a/tempest/scenario/test_baremetal_basic_ops.py b/tempest/scenario/test_baremetal_basic_ops.py
index 9415629..93b32f7 100644
--- a/tempest/scenario/test_baremetal_basic_ops.py
+++ b/tempest/scenario/test_baremetal_basic_ops.py
@@ -123,23 +123,9 @@
         # the same size as our flavor definition.
         eph_size = self.get_flavor_ephemeral_size()
         if eph_size:
-            preserve_ephemeral = True
-
             self.verify_partition(vm_client, 'ephemeral0', '/mnt', eph_size)
             # Create the test file
-            timestamp = self.create_timestamp(
+            self.create_timestamp(
                 floating_ip, private_key=self.keypair['private_key'])
-        else:
-            preserve_ephemeral = False
 
-        # Rebuild and preserve the ephemeral partition if it exists
-        self.rebuild_instance(preserve_ephemeral)
-        self.verify_connectivity()
-
-        # Check that we maintained our data
-        if eph_size:
-            self.verify_partition(vm_client, 'ephemeral0', '/mnt', eph_size)
-            timestamp2 = self.get_timestamp(
-                floating_ip, private_key=self.keypair['private_key'])
-            self.assertEqual(timestamp, timestamp2)
         self.terminate_instance()