SonarCloud error reduction: java rule S5411: Avoid using boxed "Boolean" types directly in boolean expressions

[CDellaGiusta]

SonarCloud issues errors on java rule S5411: Avoid using boxed "Boolean" types directly in boolean expressions
https://sonarcloud.io/organizations/uyuni-project/rules?open=java%3AS5411&rule_key=java%3AS5411

All issues in Uyuni for this rule:
https://sonarcloud.io/project/issues?languages=java&issueStatuses=OPEN%2CCONFIRMED&id=uyuni-project_uyuni&rules=java%3AS5411

These errors should be fixed. This task can be also split into smaller chunks.