Intent of heartbeat_timeout_without_heartbeat_details

All 2 exact tests in this concept. Every test is marked by where it enters the hierarchy.

go.temporal.io/ 2 tests
- server/ 2 tests
  - chasm/ 2 tests
    
    lib/ 2 tests
    
    activity/ 2 tests
    
    TestTransitionTimedout/ 2 tests
    
    go.temporal.io/server/chasm/lib/activity/TestTransitionTimedout/heartbeat_timeout Inherited heartbeat_timeout
    
    go.temporal.io/server/chasm/lib/activity/TestTransitionTimedout/heartbeat_timeout_without_heartbeat_details Introduced here