Remove Base_dir from non system non recovery filesystem

vendor.img/product.img... built by make do not assemble the artifacts in
a $partition subdirectory. This CL adds this to soong built img files,
and updates the symmlinks.

Test: soong_generated_system_filesystem_test m soong_generated_vendor_filesystem_test soong_generated_product_filesystem_test
Change-Id: Ia5feaf85bb49d552b93698c50998d8df7575e44a