feat: Allow for pubsub connections to optionally be taken from pool

[vtermanis]

• Suggestion for Proposal: Optionally allow for pubsub connections to be tracked in pool #2867
• Only applicable to non-cluster client
  • Question: Should it apply to all client types?

[vtermanis]

Only the RE Tests suite fails - it's not able to find an (internal?) docker image. I believe there's nothing I can do about that.

[vtermanis]

@ofekshenawa thank you for taking a look. Are you sure it's a breaking change? The way I've tried to write should mean that both from a behaviour and performance perspective it behaves as before unless the new configuration flag is explicitly set.
(Unless you mean the fact that for now it's only for the non cluster client. I didn't update those so I could age what you, the developers/maintainers, think.)