Move PRODUCT_UPDATABLE_SYSTEM_SERVER_JARS to default_art_config.mk.

The list of updatable system server jars must be known in
module_common.mk which is used to build mainline modules that contain
said system server jars.

module_common.mk inherit from default_art_config.mk.

Note that we could also move the defition into a separate make file,
if current change causes problems. However, places like clockwork
overwrite values of PRODUCT_UPDATABLE_SYSTEM_SERVER_JARS instead
of appending to them, so it should not be a source of issues.

Bug: 180105615
Bug: 190407034
Test: TARGET_BUILD_VARIANT=user vendor/google/build/build_mainline_modules.sh -j64 and inspecting build artifacts
Change-Id: I771895bf0a974a4c6aa4f7374159c22536f03891
Merged-In: I771895bf0a974a4c6aa4f7374159c22536f03891