slapos_subscription_request: Generate a password that always comply with the Authentication Policy

The password is re-set anyway later, however it is required to comply to Authentication Policy, generating an acceptable value.
4 jobs for master in 0 seconds
Status Job ID Name Coverage
  External
passed SlapOS.Eggs.UnitTest-Master.Python2

00:23:32

passed SlapOS.Eggs.UnitTest-Master.Python3

01:05:18

passed SlapOS.Eggs.UnitTest-Master.Python2

00:22:33

passed SlapOS.Eggs.UnitTest-Master.Python3

00:28:46