SI-8253 Adjust test for namespace interpolation

This test fails after we try to fix SI-8523 in the compiler.
But the test is actually at fault here, as it was relying on
the loose matching performed by the compiler's SymbolXMLBuilder.

The fix for SI-8253 that triggered the failure:

   scala/scala@8d175b907

The original commit that introduced this test:

   scala/scala@e1ffc05b10be6

Author: retronym

src/test/scala/scala/xml/XMLTest.scala

@@ -601,7 +601,7 @@ expected closing tag of foo
     </wsdl:definitions>;
 
   def wsdlTemplate3(serviceName: String): Node =
-    <wsdl:definitions name={ serviceName } xmlns:tns={ Text("target3") }>
+    <wsdl:definitions name={ serviceName } xmlns:tns={ new _root_.scala.xml.Text("target3") }>
     </wsdl:definitions>;
 
   def wsdlTemplate4(serviceName: String, targetNamespace: () => String): Node =