Back out "fix multiline string tests"

This backs out commit 0c5604b462.

tests/test_cases/input/multiline_string_whitespace_only.kdl

@@ -1,19 +1,18 @@
 // This file deliberately contains unusual whitespace
-// The first three strings are empty, because whitespace-only lines collapse to
-// just `\n`.
+// The first two strings are empty
 node """
   	""" """
  	 \
-             
+             
  	 """ """
-                             
+                            
  """\
     \ // The next two strings contains only whitespace
     """
        
-           
+       
       \s 
     """ #"""
-      
+    
 
   """#

tests/test_cases/input/multiline_string_whitespace_only_non_matching_prefix_fail.kdl

@@ -1,19 +0,0 @@
-// This file deliberately contains unusual whitespace
-// Parsing should fail because not all strings have a matching multiline prefix,
-// which must be exact, down to the codepoint, _before_ newline normalization.
-node """
-  	""" """
- 	 \
-             
- 	 """ """
-                            
- """\
-    \ // The next two strings contains only whitespace
-    """
-       
-       
-      \s 
-    """ #"""
-    
-
-  """#