Fix docker federation setup (#2706)

api_tests/src/shared.ts

crates/apub/src/lib.rs

crates/db_schema/src/utils.rs

docker/federation/docker-compose.yml

docker/federation/lemmy_alpha.hjson

docker/federation/lemmy_beta.hjson

docker/federation/lemmy_delta.hjson

docker/federation/lemmy_epsilon.hjson

docker/federation/lemmy_gamma.hjson

docker/federation/start-local-instances.bash