Integration Fixes - TODOs, Default Timeline, Code Review

Sprint 3 Integration Fixes:

1) Removes collection-related TODOs added to unblock integration.
2) Assigns a default timeline when LCA is not specified.
3) Removes "Cosmos" as the default LCA since in custom timelines we no longer know the GUID from the root timeline. (This fixes sandbox/sandbox not displaying all data).
4) Code review improvements from "Integrate ACS with Service API" code review.