test: align report key assertions with raw and computed split

The caddy and haproxy bats suites referenced `refute_output`, which is not provided by the in-tree test_helper, so the steps failed with `command not found`. The traefik `api-entry-point property` test and the logs `logs:set global` test still queried the removed bare `--traefik-api-entry-point` flag and the pre-split `--logs-global-max-size` default respectively. The assertions now use `assert_output_exists`, the `--traefik-computed-` flag, and the raw/computed key pair for `logs:set --global max-size`.

tests/unit/haproxy.bats

@@ -107,7 +107,7 @@ teardown() {
   echo "output: $output"
   echo "status: $status"
   assert_success
-  refute_output ""
+  assert_output_exists
 
   run /bin/bash -c "dokku --quiet haproxy:report --global --format json | jq -r '.\"global-refresh-conf\"'"
   echo "output: $output"