Only verify skipped buckets if present to reflect skipped bucket changes in aosp/2153240. am: f5f0131161

Original change: https://android-review.googlesource.com/c/platform/packages/modules/StatsD/+/2199810

Change-Id: Ib1ad57469c05b807aa6426dbc6db53855f23c96b
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>