FR: Remove inline docs in `client.ts`, add @example tag

[sofisl]

See googleapis/gapic-generator-typescript#981

We're not going to include:

 *
 * @example <caption>include:samples/generated/{{api.naming.version}}/{{service.name.toSnakeCase()}}.{{method.name.toSnakeCase()}}.js</caption>
 * region_tag:{{ api.naming.productName.toSnakeCase() }}_{{ method.name.toSnakeCase() }}_sample
 *

in templates/typescript_gapic/src/$version/$service_client.ts.njk

because it is not yet fully functional in cloud rad.

When it becomes functional, we will add this region tag, and delete the current @example tag that just includes inline samples).

@fhinkel to notify when this is ready.

[sofisl]

Closed by googleapis/gapic-generator-typescript#1045