les: historical data garbage collection (#19570)

This change introduces garbage collection for the light client. Historical
chain data is deleted periodically. If you want to disable the GC, use
the --light.nopruning flag.

cmd/geth/usage.go

@@ -96,6 +96,7 @@ var AppHelpFlagGroups = []flagGroup{
 			utils.UltraLightServersFlag,
 			utils.UltraLightFractionFlag,
 			utils.UltraLightOnlyAnnounceFlag,
+			utils.LightNoPruneFlag,
 		},
 	},
 	{