Option to ignore specific Postgres (`pg`) spans

[Lms24]

Problem Statement

Extracted from #16505 (comment), we should find a way to ignore certain spans emitted from the OTel pg instrumentation. For example, the pg-pool.connect spans.

Solution Brainstorm

Right now, I don't think there is a way to achieve this, given that the pg instrumentation from OTel used in our postgresIntegration doesn't expose an option for (not) starting connect spans. Which means we'll likely need to contribute this upstream or vendor-in the pg instrumentation (with pg already being Otel v2 compatible, we'd likely need to vendor-in anyway).

[Lms24]

This was already requested in open-telemetry/opentelemetry-js-contrib#2017 and we might be able to use the workaround: open-telemetry/opentelemetry-js-contrib#2017 (comment)