devtools: Fix cleanup of temporary database (closes #1908656) The stored database path for clean up was not absolute. We now make the ``db-name`` absolute at database manade initialization. before storing the name for cleanup.

if versions_map['cubicweb'][0] == (3, 7, 4):
    config['http-session-time'] *= 60
    config['cleanup-session-time'] *= 60
    config['cleanup-anonymous-session-time'] *= 60