Fix up instance types in sys meta for resizes

This adds code to the resize paths to update the system_metadata
with new (or reverted) flavor information so that resized instances
are consistent with normal ones.

It also stashes the new and old instance_type information in system_metadata
during resize, which allows us to avoid database lookups for type
information at finish, confirm, and revert time.

Related to blueprint no-db-compute

Change-Id: I7f74ef8131be7a60e3a844fdf00fdeb3683f1317
Teach resource tracker about stashed instance types

This removes instance_type-related database queries from the
resource_tracker.

Related to blueprint no-db-compute

Change-Id: Ia5dd407181fa733cc81d3ce03edc1c06c2aae762
Make cells_api fetch stashed instance_type info

Related to blueprint no-db-compute

Change-Id: If87bdd6a29d511117ce5d58057e601a155c64959
Remove remaining instance_types query from compute/manager

Related to blueprint no-db-compute

Change-Id: Ib4bf1731e408821f727f70dcc77b9883504ba960
Merge "Fix up instance types in sys meta for resizes"
Merge "Teach resource tracker about stashed instance types"
Merge "Make cells_api fetch stashed instance_type info"
Merge "Remove remaining instance_types query from compute/manager"
Merge remote-tracking branch 'citrix/master' into build-temp