Revert "libsnapshot: Don't package snapuserd.rc in /vendor/etc."

This reverts commit 68ba6695.

Bug: 174587489
Test: build and manual inspect

Reason for revert: revert workaround. Fix is in I71227d807244b.

Change-Id: I71b1c0f933eeba9dd8d8fbef3a682657f005cc3b