Align escape tests to community consensus

Author: afs

sparql11/data-r2/syntax-sparql2/syntax-esc-04.rq

@@ -1,3 +1,5 @@
 PREFIX : <http://example/> 
 SELECT *
-WHERE { <\u0078> :\u0070 ?xx\u0078 }
+## Community: \ u escapes in URIs and strings only.
+## U+0078 is 'x'
+WHERE { <\u0078> :p "xx\u0078" }

sparql11/data-r2/syntax-sparql2/syntax-esc-05.rq

@@ -1,5 +1,5 @@
 PREFIX : <http://example/> 
 SELECT *
-# Comments can contain \ u
+## Community: \ u escapes in URIs and strings only.
 # <\u0078> :\u0070 ?xx\u0078
-WHERE { <\u0078> :\u0070 ?xx\u0078 }
+WHERE { <\u0078> :p "xx\u0078" }