fix: fixes for dynamic routing and streaming descriptors (#228)

- [ ] Regenerate this pull request now.

Use gapic-generator-typescript v2.14.5.

PiperOrigin-RevId: 450616838

Source-Link: googleapis/googleapis@7a47b72

Source-Link: https://github.com/googleapis/googleapis-gen/commit/42cc6331bae0b99f61b8e01ae15b05211716c4f9
Copy-Tag: eyJwIjoiLmdpdGh1Yi8uT3dsQm90LnlhbWwiLCJoIjoiNDJjYzYzMzFiYWUwYjk5ZjYxYjhlMDFhZTE1YjA1MjExNzE2YzRmOSJ9

src/v1beta1/speech_translation_service_client.ts

@@ -162,7 +162,8 @@ export class SpeechTranslationServiceClient {
     // Provide descriptors for these.
     this.descriptors.stream = {
       streamingTranslateSpeech: new this._gaxModule.StreamDescriptor(
-        gax.StreamType.BIDI_STREAMING
+        gax.StreamType.BIDI_STREAMING,
+        opts.fallback === 'rest'
       ),
     };