Use DevStack functions in upgrade scripts

* Source target DevStack's functions in upgrade scripts to match what the
  project config functions expect.
* Source target DevStack's lib/tls in upgrade scripts that source
  target's lib/keystone (is_ssl_enabled_service())

Change-Id: Iab78d1efb7e40a3a67408f6e9a071723a3e931ff
Merge "Use DevStack functions in upgrade scripts"