[service-bus] Logic for removing links from our internal context map is incorrect and does not remove links

[richardpark-msft]

Found through inspection looking at another issue.

This code uses the wrong values for this._linkType:

    this._logger.verbose(`${this.logPrefix} permanently closing this link.`);

    // Remove the underlying AMQP link from the cache
    switch (this._linkType) {
      case "s": {
        delete this._context.senders[this.name];
        break;
      }
      case "br":
      case "sr": {
        delete this._context.messageReceivers[this.name];
        break;
      }
      case "ms": {
        delete this._context.messageSessions[this.name];
        break;
      }
    }

However, the values for _linkType are not 's', 'br', 'sr', and 'ms' - they're actually the longer form of each of those names: "batching" | "streaming" | "session" | "mgmt":

type LinkTypeT<
  LinkT extends Receiver | AwaitableSender | RequestResponseLink
> = LinkT extends Receiver
  ? ReceiverType
  : LinkT extends AwaitableSender
  ? "sender" // sender
  : LinkT extends RequestResponseLink
  ? "mgmt" // management link
  : never;

export type NonSessionReceiverType =
  | "batching" // batching receiver
  | "streaming"; // streaming receiver

export type ReceiverType = NonSessionReceiverType | "session"; // message session

This might not be a direct culprit in some bugs (the links, I believe, do get closed, it's just not cleaned up from our dictionary) but it definitely isn't correct and should be fixed.