Remove outdated test

Selecting wether to list loose or packed references is not something
we want to support anymore, so remove a test for this.

tests-clar/refs/list.c

@@ -41,17 +41,6 @@ void test_refs_list__all(void)
 	git_strarray_free(&ref_list);
 }
 
-void test_refs_list__symbolic_only(void)
-{
-   // try to list only the symbolic references
-	git_strarray ref_list;
-
-	cl_git_pass(git_reference_list(&ref_list, g_repo, GIT_REF_SYMBOLIC));
-	cl_assert(ref_list.count == 0); /* no symrefs in the test repo */
-
-	git_strarray_free(&ref_list);
-}
-
 void test_refs_list__do_not_retrieve_references_which_name_end_with_a_lock_extension(void)
 {
 	git_strarray ref_list;