[PBI] Adjust actions from pub sub service

[devkelley]

Description

Currently the actions passed from the pub sub service are START, STOP and DELETE. These should be adjusted as they are prescriptive, rather than suggestions. A suggested change would be:

START - HAS_SUBS
STOP - NO_SUBS
STOP (repeated) - NO_SUBS_TIMEOUT
DELETE - REMOVED

Acceptance criteria

• Actions are standardized between service and samples