Clear stale PIDs from cache (#8263)
Clear stale PIDs from cache (#8263)

* After restarting a process, the pids will obviously change, but the process can/usually is still live
* After a lengthy discussion with Datadog support, they suggested changing the cache values
  to avoid false positives
* This small patch should clear the cache when the cached pids cannot be found
  which will update the cache
* This way there's no need to reduce the cache size or hurt performance
  and still more accurately deal with process restarts
DataDog/integrations-core,DataDog/integrations-core,DataDog/integrations-core,DataDog/integrations-core,DataDog/integrations-core,DataDog/integrations-core,DataDog/integrations-core,DataDog/integrations-core,DataDog/integrations-core,DataDog/integrations-core