[service-bus] Test and remove old code paths that avoided 'drain'

[richardpark-msft]

There is a code path currently that attempts to avoid draining when in receiveAndDelete mode (code).

 // Action to be performed on the "message" event.
      const onReceiveMessage: OnAmqpEventAsPromise = async (context: EventContext) => {
        // TODO: this appears to be aggravating a bug that we need to look into more deeply.
        // The same timeout+drain sequence should work fine for receiveAndDelete but it appears
        // to cause problems.
        if (this._receiveMode === "peekLock") {
          if (brokeredMessages.length === 0) {

Based on the fixes made in these PRs (#12772, #12908, #13073), I'd like to see if we can still reproduce this. If not, we can remove this workaround.

Orig discussion with @chradek: #13073 (comment)

[richardpark-msft]

There was an additional fix in this area: #15989

It'd still be good to put in a perf/stress test for this that to see if this code can be eliminated altogether.

[github-actions]

Hi @richardpark-msft, we deeply appreciate your input into this project. Regrettably, this issue has remained inactive for over 2 years, leading us to the decision to close it. We've implemented this policy to maintain the relevance of our issue queue and facilitate easier navigation for new contributors. If you still believe this topic requires attention, please feel free to create a new issue, referencing this one. Thank you for your understanding and ongoing support.