Fix red develop bc16e4973da4

The merge lane found `develop` red at `bc16e4973da4b8639f2979d6dc9557ae1b2231db` on its own: no queued PR merges until it is fixed. Failing (tests and gate stages): - `tests/billing/test_authz_matrix.py::test_every_billing_route_has_a_matrix_row` - `tests/billing/test_routes.py::test_every_billing_write_is_a_registered_console_action` - `api-unit-dc-test` The whole gate log: artifact `8204` on lane task 8931. Make `develop` pass its full gate again. Open a PR as usual: the merge lane merges a PR that fixes some of these and adds no failure even while `develop` is red.

Registered Task 8913's POST /api/billing/orgs/{org_id}/trial in the billing authz matrix and WRITE_ROUTES (tests only). Billing suites: 318 passed. Quick gate green. PR #6607 queued to the merge lane. Memory: none applied.