Add pre ping lifo params to sqlalchemy

[moshe]

When setting https://postgresqlco.nf/doc/en/param/idle_session_timeout/ , Postgres kills connections which idle for more than idle_session_timeout seconds. Due to the facts that danswer default pool size is pretty big (40 connections), some connections get killed before used, which raise SSL errors.

May be related to:
#1622
#1625

Running in production for 5 days without any issue so far

[vercel]

@moshe is attempting to deploy a commit to the Danswer Team on Vercel.

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