fix: avoid unhandled exception on streamingRecognize

[orgads]

• Execute streamingRecognize
• When done, close the client
• Execute streamingRecognize again, with data already in the stream
• Unhandled exception occurs.

TypeError [ERR_INVALID_ARG_TYPE]: The "chunk" argument must be of type string or an instance of Buffer or Uint8Array. Received an instance of Object
    at _write (node:internal/streams/writable:474:13)
    at Writable.write (node:internal/streams/writable:502:10)
    at Duplexify._write (/project/node_modules/duplexify/index.js:212:22)
    at doWrite (/project/node_modules/duplexify/node_modules/readable-stream/lib/_stream_writable.js:390:139)
    at writeOrBuffer (/project/node_modules/duplexify/node_modules/readable-stream/lib/_stream_writable.js:381:5)
    at Writable.write (/project/node_modules/duplexify/node_modules/readable-stream/lib/_stream_writable.js:302:11)
    at Pumpify.<anonymous> (/project/node_modules/@google-cloud/speech/build/src/helpers.js:79:27)
    at Object.onceWrapper (node:events:633:26)
    at Pumpify.emit (node:events:518:28)
    at obj.<computed> [as _write] (/project/node_modules/stubs/index.js:28:22)
    at doWrite (/project/node_modules/duplexify/node_modules/readable-stream/lib/_stream_writable.js:390:139)
    at writeOrBuffer (/project/node_modules/duplexify/node_modules/readable-stream/lib/_stream_writable.js:381:5)
    at Writable.write (/project/node_modules/duplexify/node_modules/readable-stream/lib/_stream_writable.js:302:11)
    at PassThrough.ondata (node:internal/streams/readable:1007:22)
    at PassThrough.emit (node:events:518:28)
    at addChunk (node:internal/streams/readable:559:12) {
  code: 'ERR_INVALID_ARG_TYPE'

This happens because streamingRecognize writes streamingConfig on first chunk. Usually the stream is open in object mode, so it works, but when the client is terminated, PassThrough is used without object mode.

Change PassThrough to object mode, so it terminates gracefully.

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Fixes #5464 🦕

[sofisl]

/gcbrun

[sofisl]

/gcbrun