Fix and simplify the check for minion installed packages
Fix and simplify the check for minion installed packages

- remove Background ("Given this client hostname" has been removed)
- use "Given I am on the Systems overview page ..." instead
- no need to verify again that this client is registered
- no need to assign the Management entitlement
- instead verify that the SaltStack entitlement is assigned

SUSE/spacewalk-testsuite-base,MalloZup/spacewalk-testsuite-base,0rnela/spacewalk-testsuite-base