Prevent systemserverclasspath_fragment from depending on prebuilts

When TARGET_BUILD_APPS is set then TARGET_BUILD_USE_PREBUILT_SDKS=true
which causes all java_sdk_library_import modules to be treated as
prefer:true.

That breaks the build when the systemserverclasspath_fragment's content
property references a source java_sdk_library module that has a
corresponding java_sdk_library_import prebuilt module.

This fixes the issue by marking the dependency from the
systemserverclasspath_fragment to the source module as one that must
not be replaced with a reference to the prebuilt module.

Test: - update art prebuilts to include service-art
      m TARGET_BUILD_APPS=Calendar apps_only
      - fails before, works afterwards
Bug: 199116972
Change-Id: Ia2d8ce7bb7e644336a42c901f7fb8ea50fd67909