Lower per-app notificationchannel limit

Test: PreferencesHelperTest
Bug: 240422263
Change-Id: I8c12e3fc73e4a88842af275feaf2acffcced0402
(cherry picked from commit f528b337dd48b7e8071269e07e610bd4a3668c75)
(cherry picked from commit 39b4b1e9aad79c98413a866de53ccacccf64ca7f)
Merged-In: I8c12e3fc73e4a88842af275feaf2acffcced0402
1 file changed