feat(core): Make postgres pool-size configurable (no-changelog) (#7772)

When we upgrade typeorm in #5151, we switched from no pooling to a
default pool-size of 10. This somehow significantly deteriorates the
performance of queries when the application is under load.

packages/cli/src/config/schema.ts

@@ -91,6 +91,12 @@ export const schema = {
 				default: 'public',
 				env: 'DB_POSTGRESDB_SCHEMA',
 			},
+			poolSize: {
+				doc: 'PostgresDB Pool Size',
+				format: Number,
+				default: 2,
+				env: 'DB_POSTGRESDB_POOL_SIZE',
+			},
 
 			ssl: {
 				enabled: {