Skip NumberFormatTest#testMonetarySeparator on U or below am: 6d2364d5ea am: 921400dd8d

Original change: https://android-review.googlesource.com/c/platform/external/icu/+/3125253

Change-Id: Iba0d2b9dd647d1d76bc5febba70f949b7f8dcef9
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>