Fix run_instance() rpc method to pass instance object

Change I8a206f63cab1e4f939d2c97c258312a8fa540aff converted run_instance()
to use instance objects, but although it changed the rpc version to 3.27
it didn't update the rpcapi method, so at the moment it still passes a
dict.

Related to blueprint compute-manager-objects-juno

Change-Id: I0e511a5c4f1adce901f8812a935b98886c216dc9
Merge "Fix run_instance() rpc method to pass instance object"