Remove unhelpful code snippet at the top of all non-overview pages

There is a code snippet on top of all the non-overview (e.g. it exists on all pages except for the Library Overview, the Client Overview, and the Package Overview pages) pages that is not useful.

For example on top of the [`SpeechSettings`](https://cloud.google.com/java/docs/reference/google-cloud-speech/latest/com.google.cloud.speech.v2.SpeechSettings) class:

The [`BatchRecognizeRequest`](https://cloud.google.com/java/docs/reference/google-cloud-speech/latest/com.google.cloud.speech.v2.BatchRecognizeRequest) class:

The [`AutoDetectDecodingConfig.Builder'](https://cloud.google.com/java/docs/reference/google-cloud-speech/latest/com.google.cloud.speech.v2.AutoDetectDecodingConfig.Builder) class:

I assume the doclet is generating something that is causing that to show up - this bug is to investigate where it's coming from and ideally removing it.

Inizia tracciando l'output Javadoc del doclet fino ai file YAML generati utilizzati da DocFX, confrontando le pagine non di overview con le pagine Library Overview, Client Overview e Package Overview. Individua dove viene generato lo snippet di codice superiore non utile e verifica che sia assente nelle pagine non di overview, mentre le pagine di overview rimangono invariate.

Scritto dal modello di indicizzazione a partire dal testo della issue.