Allow jarjar com.android.server*

Jarjar com.android.server* and adjust the test by jarjar
FrameworksNetTestsLib to make sure the test cases still can access
package sope fields. Don't auto-jarjar non-connectivity module tests
in FrameworksNetTests because some non-connectivity module test cases
rely on service.core and service.net. The reason why not auto-jarjar
whole ConnectivityCoverageTests because tethering doesn't adopt
auto-jarjar-gen yet. The coverage test must jarjar the same as module so
that test coverage can calculate correctly.

Remove com.android.server* from proguard becasue it already be covered
by android.net* after jarjar'ed.

Move MetricsTestUtil to non connectivity module test group because it
only be used for IpConnectivityEventBuilderTest which is non connectivity
module test. Only jarjar the util without jarjar the caller make the test
failure.

Bug: 248001529
Test: atest ConnectivityCoverageTests FrameworksNetTests

Change-Id: I8439341ef4c03f29697fdf34557ea8ef2825d691