merlin: roll back changes in default-based-context test

Signed-off-by: Javier Chávarri <javier.chavarri@gmail.com>

test/blackbox-tests/test-cases/merlin/default-based-context.t/run.t

@@ -13,20 +13,14 @@ If Merlin field is absent, default context is chosen
 
   $ dune build
 
-The rules are generated for all contexts, regardless which one is chosen
-
-  $ ls -a _build/cross/.merlin-conf
-  .
-  ..
-  lib-foo
+  $ [ ! -d _build/cross/.merlin-conf ] && echo "No config in cross"
+  No config in cross
 
   $ ls -a _build/default/.merlin-conf
   .
   ..
   lib-foo
 
-But the default context is used by default
-
   $ dune ocaml merlin dump-config "$PWD"
   Foo: _build/default/foo
   ((STDLIB OPAM_PREFIX)
@@ -62,10 +56,8 @@ If Merlin field is present, this context is chosen
   ..
   lib-foo
 
-  $ ls -a _build/default/.merlin-conf
-  .
-  ..
-  lib-foo
+  $ [ ! -d _build/default/.merlin-conf ] && echo "No config in default"
+  No config in default
 
   $ dune ocaml merlin dump-config "$PWD"
   Foo: _build/cross/foo