Since the commit c219a3efc6622c6e5857577d94633efc7d139860
removed js file 'horizon.instances.js' in the template file
' _scripts.html', If enable the legacy experience launch instance
(Set 'LAUNCH_INSTANCE_LEGACY_ENABLED = True' and
'LAUNCH_INSTANCE_NG_ENABLED = False' in the local_settings.py) and
click launch instance, we can not open launch instance dialog and
also see the following in console.log.
VM22778:3 Uncaught TypeError: Cannot read property 'workflow_init'
of undefined
Change-Id: Ia9e22df5129527e4b021599bbdec9a668a04ee4b
Closes-Bug: #1686431