Lower per-app notificationchannel limit Test: PreferencesHelperTest Bug: 240422263 Change-Id: I8c12e3fc73e4a88842af275feaf2acffcced0402 Merged-In: I8c12e3fc73e4a88842af275feaf2acffcced0402 (cherry picked from commit f528b337dd48b7e8071269e07e610bd4a3668c75)