tests: Correctly skip single fsverity test

The skip shell function is for skipping an entire test plan. To skip a
single test result, a directive is needed[1]. Without this change, the
test suite errors claiming that 2 test plans were provided when fsverity
isn't available.

1. https://testanything.org/tap-specification.html#skipping-tests

tests/test-rofiles-fuse.sh

@@ -208,5 +208,5 @@ if fsverity enable checkout-test2/nonhardlinked 2>err.txt; then
     assert_not_streq "${orig_inode}" "${new_inode}"
     echo "ok copyup fsverity"
 else
-    skip "no fsverity support: $(cat err.txt)"
-fi
+    echo "ok copyup fsverity # SKIP no fsverity support: $(cat err.txt)"
+fi