* ci: port the Postgres suites off CircleCI onto service containers
proxy_behavior_tests, proxy_security_tests and schema_migration_check were
near-identical CircleCI jobs: a Postgres sidecar, a schema seed, and one pytest
tree each. They ran nowhere else, and CircleCI holds none of the branch
ruleset's required checks, so the signal they produced gated nothing.
test-postgres.yml runs the same three trees on a Postgres service container as
one matrix, keeping each suite's own seeding rather than normalising it: the
behavior and security trees keep `prisma db push`, and the migration tree keeps
an empty database, which is what it needs to apply every committed migration
itself.
Their CircleCI definitions and workflow entries go with them, taking the config
from 47 jobs to 44. assert_ci_coverage.py stays green: dropping the new
workflow fails the census on exactly these trees, so the coverage moved rather
than went missing.
auth_ui_unit_tests is deliberately left behind. Ported, two of its
tests fail because prepare_metadata_fields refuses enterprise-only keys without
LITELLM_LICENSE, which exists as a CircleCI project variable and has no
GitHub Actions secret. Creating that secret is a human action, so the job stays
on CircleCI until it exists rather than shipping a red shard or quietly
deselecting the two tests.
* chore(ci): drop the narrative header from test-postgres.yml
