Refactoring GlobalSettingsProto to avoid method limit.

This is a large CL, so I'll do the other two protos in separate CLs.

Bug: 76011704
Bug: 74975371
Test: flash device and check incident.proto output
Change-Id: I285e6495b122c36eded9f6fc3afa39c92c293ed5
also: m EMMA_INSTRUMENT_STATIC=true EMMA_INSTRUMENT=true out/target/common/obj/APPS/CtsStatsdApp_intermediates/jacoco/work/instrumented/updated.stamp
also: atest CtsIncidentHostTestCases:com.android.server.cts.SettingsIncidentTest