cubicweb #1618089 postgres test doesn't properly reuse db template (see unittest_postgres) [resolved]

as they used to before the test database refactoring

prioritynormal
typebug
done in3.11.3
load0.200
load left0.000
closed by#70538ea2532d [testlib] fix readlb config handling, avoid systematic recreation of db with postgres (closes #1618089)