CB-14225 fix sample Namespace Serialize attribute in template/Properties/Default.rd.xml

[brodycj]

Original issue

https://issues.apache.org/jira/browse/CB-14225

Platforms affected

Windows

What does this PR do?

• Fix sample Namespace Serialize attribute in template/Properties/Default.rd.xml, according to Default.rd.xml in C# UWP project generated by Visual Studio 2017

I also raised microsoft/Windows-universal-samples#950 to apply a similar fix there.

Also related:

• CB-14224 Default.rd.xml header fixes #284 - fix license text & add link to template/Properties/Default.rd.xml (as reported in https://issues.apache.org/jira/browse/CB-14224)
• Fix license txt microsoft/Windows-universal-samples#949 - fix license txt (related to but not part of CB-14224 Default.rd.xml header fixes #284)

What testing has been done on this change?

• Visual inspection
• check diff

Checklist

• Reported an issue in the JIRA database
• Commit message follows the format: "CB-3232: (android) Fix bug with resolving file paths", where CB-xxxx is the JIRA ID & "android" is the platform affected.
• Added automated test coverage as appropriate for this change.