fix: make sure to correctly initialize health checks (#17765)

health checks were missing for drives replaced since

- HealFormat() would replace the drives without a health check
- disconnected drives when they reconnect via connectEndpoint()
  the loop also loses health checks for local disks and merges
  these into a single code.
- other than this separate cleanUp, health check variables to avoid
  overloading them with similar requirements.
- also ensure that we compete via context selector for disk monitoring
  such that the canceled disks don't linger around longer waiting for
  the ticker to trigger.
- allow disabling active monitoring.

cmd/generic-handlers.go

@@ -207,7 +207,7 @@ func getRedirectLocation(r *http.Request) *xnet.URL {
 }
 
 // guessIsHealthCheckReq - returns true if incoming request looks
-// like healthcheck request
+// like healthCheck request
 func guessIsHealthCheckReq(req *http.Request) bool {
 	if req == nil {
 		return false