remove logic added per OOIION-1551, which is now obsolete.

Related old commit: https://github.com/ooici/coi-services/commit/763a90d0edfe
remove a TODO comment as it seems there's actually no need to pass child's alerts_list when publishing a rollup status update from parent platform
remove/update some TODO comments in platform agent
organize imports according to ci code conventions
organize imports according to ci code conventions
Merge pull request #2221 from carueda/pa_more_cleanup

PA more cleanup