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

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

Change-Id: I7bf56468a4cab1186a01485acd78a8b4d1c2c0f8
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>