Remove legacy GitHub API cache of HRA.Status.CachedEntries (#1192)

* Remove legacy GitHub API cache of HRA.Status.CachedEntries

We migrated to the transport-level cache introduced in #1127 so not only this is useless, it is harder to deduce which cache resulted in the desired replicas number calculated by HRA.
Just remove the legacy cache to keep it simple and easy to understand.

* Deprecate githubAPICacheDuration helm chart value and the --github-api-cache-duration as well

* Fix integration test

controllers/autoscaling.go

@@ -7,7 +7,6 @@ import (
 	"math"
 	"strconv"
 	"strings"
-	"time"
 
 	"github.com/actions-runner-controller/actions-runner-controller/api/v1alpha1"
 	"github.com/google/go-github/v39/github"
@@ -20,47 +19,6 @@ const (
 	defaultScaleDownFactor    = 0.7
 )
 
-func getValueAvailableAt(now time.Time, from, to *time.Time, reservedValue int) *int {
-	if to != nil && now.After(*to) {
-		return nil
-	}
-
-	if from != nil && now.Before(*from) {
-		return nil
-	}
-
-	return &reservedValue
-}
-
-func (r *HorizontalRunnerAutoscalerReconciler) fetchSuggestedReplicasFromCache(hra v1alpha1.HorizontalRunnerAutoscaler) *int {
-	var entry *v1alpha1.CacheEntry
-
-	for i := range hra.Status.CacheEntries {
-		ent := hra.Status.CacheEntries[i]
-
-		if ent.Key != v1alpha1.CacheEntryKeyDesiredReplicas {
-			continue
-		}
-
-		if !time.Now().Before(ent.ExpirationTime.Time) {
-			continue
-		}
-
-		entry = &ent
-
-		break
-	}
-
-	if entry != nil {
-		v := getValueAvailableAt(time.Now(), nil, &entry.ExpirationTime.Time, entry.Value)
-		if v != nil {
-			return v
-		}
-	}
-
-	return nil
-}
-
 func (r *HorizontalRunnerAutoscalerReconciler) suggestDesiredReplicas(st scaleTarget, hra v1alpha1.HorizontalRunnerAutoscaler) (*int, error) {
 	if hra.Spec.MinReplicas == nil {
 		return nil, fmt.Errorf("horizontalrunnerautoscaler %s/%s is missing minReplicas", hra.Namespace, hra.Name)