Revert "Don't restore notification channel if its sound is unavailable" am: cc547d33 am: 798e21e4 am: e146e77b

Original change: https://googleplex-android-review.googlesource.com/c/platform/frameworks/base/+/15718202

Change-Id: Ibb19dbe4d5b8fd89237e6f49da649a1da4ab6dcf