Remove --hide-package options from droidstubs

The `--hide-package com.android.server` option had no effect as the
`com.android.server` subpackages have `package-info.java` files with
`/** @hide */`.

The `--hide-package android.audio.policy.configuration.V7_0` option did
hide classes from that package from the API, presumably because those
classes are already managed by `audio_policy_configuration_V7_0`. This
change replicates that behavior by adding a `package-info.java` file
with `/** @hide */` in that package.

Bug: 351991463
Test: m checkapi
Change-Id: I9a11512daaa6fbbca245518e456b09a12cdf7ebc