Add validation of db encryption keys to cc_ng pre start migrations (#538)

* Add validation of db encryption keys to cc ng pre start

* adapt behaviour from pre-start script to be consistent

* fix formatting

Author: kathap

jobs/cloud_controller_ng/templates/bin/cloud_controller_ng.erb

@@ -12,6 +12,9 @@ echo 'Running migrations and seeds'
 /var/vcap/jobs/cloud_controller_ng/bin/migrate_db
 /var/vcap/jobs/cloud_controller_ng/bin/seed_db
 echo 'Finished migrations and seeds'
+<% if !p('cc.database_encryption.skip_validation') %>
+/var/vcap/jobs/cloud_controller_ng/bin/validate_encryption_keys
+<% end %>
 <% end %>
 
 <% if p('cc.experimental.use_yjit_compiler') %>