Consider migrating from pumpify to pipeline or to Readable.from

[leahecole]

The pumpify library for streams can be a bit flaky. Recommending that when someone has time, to consider using pipeline or Readable.from instead.

Readable.from example:

async function* concatStreams(streams: ReadableStream[]) {
  for (const stream of streams) {
    yield* stream;
  }
}

const readable = Readable.from(concatStreams());

(Original comment from a thread in a gax PR https://github.com/googleapis/gax-nodejs/pull/1653#discussion_r1764032623)