incidentd: Updating field IDs and a field name.

Field 7 was removed in http://ag/3248090. Since the protos aren't being
used yet, I want to update the rest of the IDs to avoid confusion in the
future when they start being used.
Also updated a field name to better reflect what the value is.

Bug: 65750801
Test: $ cts-tradefed run cts-dev --module CtsIncidentHostTestCases --test com.android.server.cts.AlarmManagerIncidentTest
Change-Id: I48724d461fa2e68dfaf452f01a84031d9fa4180e