Use sync_on_startup in placement-perfload job

Use the [placement_database]/sync_on_startup config setting to
have the database schema synchronized during web-service startup
rather than through a separate call to placement-manage.

This is done for two reasons:

* It provides a reaonable test that it works, which is not present
  in other integration tests.
* Until Id9bc515cee71d629b605da015de39d1c9b0f8fc4 merges it will
  demonstrate the bug described in the story linked below.

Couple of things to note:

* The tempest job will continue to exercise placement-manage, as it
  has always done.
* The bug (in the story) doesn't impact the behavior of the API, it
  merely impacts what is or is not logged. In the
  logs/placement-api.log generated in the perfload job for this change
  there will be an initial burst of DEBUG and INFO logging, but then
  only request logging. This should be corrected by
  Id9bc515cee71d629b605da015de39d1c9b0f8fc4

Change-Id: Ib7f5cdfa3b314af7681d594dccb553bddb764224
Story: 2005187

playbooks/perfload.yaml

@@ -32,10 +32,9 @@
           export OS_PLACEMENT_DATABASE__CONNECTION=mysql+pymysql://root:secret@127.0.0.1/placement?charset=utf8
           export OS_PLACEMENT_DATABASE__MAX_POOL_SIZE=25
           export OS_PLACEMENT_DATABASE__MAX_OVERFLOW=100
+          export OS_PLACEMENT_DATABASE__SYNC_ON_STARTUP=True
           export OS_DEFAULT__DEBUG=True
           export OS_API__AUTH_STRATEGY=noauth2
-          # sync tables
-          placement-manage db sync
           uwsgi --http :8000 --wsgi-file .placement/bin/placement-api --daemonize {{ ansible_user_dir }}/logs/placement-api.log --processes 5 --threads 25
     - name: placement performance
       args: