Fix Postgres detector

[rosecodym]

Description:

• Use all found URIs in a chunk, rather than just the first one
• Test locally on a port other than 5433, because that one can have local dev problems
• Stop manufacturing candidate secrets with "localhost" as a candidate host
  • ignore if it it's in the chunk
  • don't conjure it up as a default
• Make it so that if "localhost" is found in a chunk, the "host" part of it doesn't trigger the host detection pattern

Checklist:

• Tests passing (make test-community)?
• Lint passing (make lint this requires golangci-lint)?

[rosecodym]

closed in favor of #2314