Replaced deprecated CaseInsensitiveComparator with java.lang.String one in tests

[StefanSpieker]

Replaced deprecated CaseInsensitiveComparator with java.lang.String one in tests

Proposed changelog entries

• N/A

Submitter checklist

• JIRA issue is well described
• Changelog entry appropriate for the audience affected by the change (users or developer, depending on the change).
  * Use the Internal: prefix if the change has no user-visible impact (API, test frameworks, etc.)
• Appropriate autotests or explanation to why this change has no tests

[jglick]

Is there a reason to change this here, when the occurrence is in old data (presumably some older version of Jenkins, if not the current, did save XML in this format)?

[StefanSpieker]

I want to create a PR to remove the CaseInsensitiveComparator from hudson.util and I am not sure if there might be a unit test failure in a distant future because of this change.

[jglick]

Well I think the existence of this test data is a good signal that you should not remove that class, at least not without some careful analysis of where it might be used in config.xmls in the field, and a plan to migrate those.

[jglick]

Seems to be serving a useful function for checking backward compatibility of settings.