Refactoring SystemSettingsProto to avoid method limit.

Bug: 76011704
Bug: 74975371
Test: flash device and check incident.proto output
and m EMMA_INSTRUMENT_STATIC=true EMMA_INSTRUMENT=true out/target/common/obj/APPS/CtsStatsdApp_intermediates/jacoco/work/instrumented/updated.stamp
and atest CtsIncidentHostTestCases:com.android.server.cts.SettingsIncidentTest

Change-Id: I30bb0f35dacd55c11603f9f8b9888c7d35df7a54