[QA] empty password is still possible, when min password lenght is defined

[jnweiger]

Seen in password_policy 2.1.3

• occ app:enable password_policy

• admin visits security settings and sets a minimim password length to 8:
  

• when we create a public link, it is still possible to set a link without a password
  

Expected behaviour:

• password policy should be able to enforce setting a password
  (either by minimum length, or by an explicit extra switch)