COMP: Fix XML namespace of Natvis file (Visual Studio Debug Visualizers)

The ITK Debug Visualizers for Visual Studio do not seem to work when the XML
namespace name starts with "https" (rather than just "http"). This was found by
enabling "Natvis diagnostic messages" in Visual Studio 2019 (version 16.11.31).
It says:

> ITK.natvis(4,2): Fatal error: Expected element with namespace 'http://schemas.microsoft.com/vstudio/debugger/natvis/2010'.

Reverts the change of this particular file from pull request InsightSoftwareConsortium#3428
commit 9cd0f20 "ENH: Use https instead of http
when https works", May 18, 2022.

-- With help from my colleagues at LKEB, Leiden University Medical Center.

Utilities/Debugger/ITK.natvis

@@ -1,7 +1,7 @@
 <?xml version="1.0" encoding="utf-8" ?>
 <!-- Documentation: https://msdn.microsoft.com/en-us/library/jj620914.aspx?f=255&MSPPError=-2147217396 -->
 <!-- e.g. copy into C:\Program Files (x86)\Microsoft Visual Studio\2017\Community\Common7\Packages\Debugger\Visualizers\ITK.natvis -->
-<AutoVisualizer xmlns="https://schemas.microsoft.com/vstudio/debugger/natvis/2010">
+<AutoVisualizer xmlns="http://schemas.microsoft.com/vstudio/debugger/natvis/2010">
 
   <Type Name="itk::Size&lt;1&gt;">
     <DisplayString>[{m_InternalArray[0]}]</DisplayString>