Anonymous: Add configurable device limit (#79265)

* Anonymous: Add device limiter

* break auth if limit reached

* fix typo

* refactored const to make it clearer with expiration

* anon device limit for config

---------

Co-authored-by: Eric Leijonmarck <eric.leijonmarck@gmail.com>

pkg/services/anonymous/anonimpl/api/api.go

@@ -15,9 +15,7 @@ import (
 	"github.com/grafana/grafana/pkg/util"
 )
 
-const (
-	thirtyDays = 30 * 24 * time.Hour
-)
+const anonymousDeviceExpiration = 30 * 24 * time.Hour
 
 type deviceDTO struct {
 	anonstore.Device
@@ -70,7 +68,7 @@ func (api *AnonDeviceServiceAPI) RegisterAPIEndpoints() {
 //	404: notFoundError
 //	500: internalServerError
 func (api *AnonDeviceServiceAPI) ListDevices(c *contextmodel.ReqContext) response.Response {
-	fromTime := time.Now().Add(-thirtyDays)
+	fromTime := time.Now().Add(-anonymousDeviceExpiration)
 	toTime := time.Now()
 
 	devices, err := api.store.ListDevices(c.Req.Context(), &fromTime, &toTime)