[Issue 2665] Analytics jobs conditionally use IAM token as Postgres pwd

[DavidDudas-Intuitial]

Summary

Fixes #2665

Time to review: 2 mins

Changes proposed

What was added, updated, or removed in this PR.

Adds a switch in analytics/integrations/db.py that determines which value to use for a DB password when connecting to Postgres: either the value in local.env or an IAM token, depending on an environment variable.

Also adds better exception handling, to make errors easier to spot in CI.

Context for reviewers

Testing instructions, background context, more in-depth details of the implementation, and anything else you'd like to call out or ask reviewers. Explain how the changes were verified.

This is a follow up to previous PRs, #2786 and #2796, and part of an effort to get analytics step functions to successfully connect to Postgres DB in a CI environment.

Additional information

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