Apply proper locks onto the service/association state tracking

As they should be locked with the ProcessStatsService lock.

Bug: 194991626
Test: Manual - build & boot
Test: atest ProcStatsValidationTests
Test: atest ProcessStatsDumpsysTest
Test: atest CtsIncidentHostTestCases:ProcStatsProtoTest
Test: atest CtsAppTestCases
Change-Id: I18ccd3f4509ba0ee00434012ed47abf81da9c907