Explicitly exclude com.android.server from docs

With the move to OpenJDK 9 the packages under
com.android are not automatically hidden. There's
only two which show up, one of which
(com.android.internal.util) was already present.
com.android.server can just be explicitly hidden.

Test: make docs / diff
Bug: 69736344
Bug: 69736236
Change-Id: I44fb16e86a8d87152eba4e53a7b2d2290662bb63