feat: auto cleanup of offline runners (#7803)

Fixes #7646

Adds a cron job to cleanup action runners that have been offline or inactive for X amount of time.

Reviewed-on: https://codeberg.org/forgejo/forgejo/pulls/7803
Reviewed-by: Gusted <gusted@noreply.codeberg.org>
Co-authored-by: Julian Schlarb <julian.schlarb@denktmit.de>
Co-committed-by: Julian Schlarb <julian.schlarb@denktmit.de>

services/cron/setting.go

@@ -46,6 +46,13 @@ type CleanupHookTaskConfig struct {
 	NumberToKeep int
 }
 
+// CleanupOfflineRunnersConfig represents a cron task with settings to clean up offline-runner
+type CleanupOfflineRunnersConfig struct {
+	BaseConfig
+	OlderThan       time.Duration
+	GlobalScopeOnly bool
+}
+
 // GetSchedule returns the schedule for the base config
 func (b *BaseConfig) GetSchedule() string {
 	return b.Schedule