[SettingsProvider] use JobScheduler.forNamespace to avoid conflicting jobs

Job IDs needs to be unique per UID, but SettingsProvider shares the
system UID so there's high chance of job-id collision. Use
JobScheduler.forNamespace to avoid it.

BUG: 289319662
Test: manual by changing job criteria and observe the job is executed
Change-Id: I577732e4f0d5bc13287790a17b59f1a42083feae