internal/postgres: redact password in error messages
internal/postgres: redact password in error messages

Change-Id: I487f1dd3d6e925b1d95a2ddd7726d7a1b4ed9e42
Reviewed-on: https://team-review.git.corp.google.com/c/golang/discovery/+/599091
CI-Result: Cloud Build <ea5729d4cf3392b9d382b6ca272c65aa27554f44@system.gserviceaccount.com>
Reviewed-by: Julie Qiu <e6cb64861edcc38971590ff27c111e0e672de045@google.com>

golang/pkgsite,golang/pkgsite,golang/pkgsite,golang/pkgsite