Pool should check for max idle lifetime in cleaner

[Sytten]

Currently the idle lifetime is only checked when the connection is requested.
It should also be checked by the cleaner.
Imagine the following scenario:

• You have a low idle lifetime but no max lifetime
• You have a rush of load on your system, the pool lends a bunch of connections
• Your system returns to normal load
• The connections are never freed because nobody request them
  This is the situation faced by issue with connection pool ? prisma/prisma#7644

I will push a fix soon