Not able switch to certbot certificates if self-signed was used before

[fleimgruber]

Steps to reproduce:

1. docker compose up with SSL_CERTIFICATE_GENERATION: "self-signed"
2. docker compose up with SSL_CERTIFICATE_GENERATION: "certbot"

docker compose logs zulip:

docker-zulip-zulip-1  | === End Bootstrap Phase ===
docker-zulip-zulip-1  | Certbot is not scheduled to run.
docker-zulip-zulip-1  | === Begin Run Phase ===

where I expected Certbot to run.