Remove unused java_sdk_library_import properties

The properties are just passed through to the java_import module that
it creates to import the stubs so could be used if set. However, none
of the current usages of java_sdk_library_import actually set them and
it is not clear why the following would ever be set on
java_sdk_library_import:
* installable
* exclude_files
* exclude_dirs

The above properties look as though they were simply copied from the
ImportProperties struct.

The libs property is also unused but it seems as though it should be
used to improve compatibility with the source module. e.g.
the source module for android.test.runner has android.test.base and
android.test.mock in its libs. However, the prebuilt version of it
does not.

Bug: 148080325
Test: m nothing
Change-Id: I710e3962b2e34b2b0cc81685d07d4948cef4e6ad