Do not test maintainers type incorrectly
Remove an incorrect test for maintainer object type, which leads to maintainer property dictionaries being pasted into XML like this:
<param name="CKI_MAINTAINERS" value="{'name': 'Memory Management', 'email': 'mm-qe@redhat.com'}, {'name': 'Jan Stancek', 'email': 'jstancek@redhat.com'}"/>
The test was trying to differentiate the old maintainer representation as a list of strings and the new representation as a list of dictionaries, but was incorrect.
Removing the test and the handling of the old format fixes the issue and the XML now looks like this:
<param name="CKI_MAINTAINERS" value="Memory Management <mm-qe@redhat.com>, Jan Stancek <jstancek@redhat.com>"/>