CI #322 caught the contextcheck violation: insertIssuerForCRL took ctx
but called getTestDB(t) which has no ctx-aware variant — propagating
the ctx through the boundary trips the linter. Drop the ctx parameter
and use context.Background() for the single ExecContext call inside
the helper; per-test isolation comes from the schema-per-test pattern
(getTestDB.freshSchema), not from ctx cancellation.