* Revert "Temporarily disable zypper tests due to timeouts."
This reverts commit 25f943e22f.
* Revert "Disable zypper_repository tests due to errors."
This reverts commit 5833197a19.
This change corrects problems reported by the `yamllint` linter.
Since key duplication problems were removed in 4d48711, this commit
mainly fixes trailing spaces and extra empty lines at beginning/end of
files.