Add package name to unregister dumpsys events

Once unregistered, the dumpsys doesn't contain any more
info that we can cross-reference the id with. By including
the package name, at least we get some idea of where the
associated requests were coming from.

Test: Manually, using adb shell dumpsys media_router.
Bug: 243116883
Change-Id: I9d8c3187fcff9f495a2f5cc0859235674a61d52a