Each package that exercises the database against a real Postgres
carried its own copy of the connection bootstrap and schema setup.
Those copies had already drifted: some keyed off PROBO_TEST_PG_ADDR
with hardcoded defaults, others off PROBO_TEST_PG_URL, and the
agentrun/coredata suites hand-applied individual agent_runs
migrations to ensure the table existed.
Introduce a single test.PGClient helper that parses PROBO_TEST_PG_URL
(falling back to the local compose database), runs the full coredata
migration set once per process, and skips when no database is
reachable so make test stays a pure unit-test run. Migrate the
agentrun, coredata, cookiebanner, iam, and thirdparty suites onto it
and delete the duplicated helpers so the bootstrap can no longer
diverge.
Signed-off-by: Bryan Frimin <bryan@probo.com>