Get library parameters from service yaml if they exist

[JoeWang1127]

Current, most of the library parameters, e.g., api_shortname, api_description, etc., comes from the generation configuration.

Some parameters can be read from service yaml and we can remove them from the generation configuration, which makes the parameters accurate because service yaml is the source of truth.

A internal project (b/337770400) is trying to consolidate all parameters into service yaml.