Fix name conflict in path of decorators test template

This test template shared the same "path" as its sibling,
cls-decl-decorators-valid-syntax.template. That meant that these two
templates would race to generate the same test files with different
contents.

This prefixes the generated tests for class element decorators (as opposed
to class decorators) with "class-element-".

src/decorator/syntax/valid/cls-element-decorators-valid-syntax.template

@@ -4,7 +4,7 @@
 /*---
 esid: prod-ClassDeclaration
 name: Valid syntax for decorator on class.
-path: language/statements/class/decorator/syntax/valid/
+path: language/statements/class/decorator/syntax/valid/class-element-
 info: |
   ClassElement[Yield, Await] :
     DecoratorList[?Yield, ?Await]opt MethodDefinition[?Yield, ?Await]