Implement beacon db pruner (#14687)

* implement weak subjectivity pruner

* fix goimports

* add delete before slot method to database

* add method to interface

* update changelog

* add flags

* wire pruner

* align pruner with backfill service

* rename db method

* fix imports

* delete block slot indices

* check for backfill and initial sync

* add tests

* fix imports

* Update beacon-chain/db/kv/blocks.go

Co-authored-by: Radosław Kapka <rkapka@wp.pl>

* Update cmd/beacon-chain/flags/base.go

Co-authored-by: Preston Van Loon <pvanloon@offchainlabs.com>

* Update beacon-chain/db/pruner/pruner.go

Co-authored-by: Radosław Kapka <rkapka@wp.pl>

* cleanup

* fix buildkite

* initialise atomic bool

* delete data from remaining buckets

* fix build

* fix build

* address review comments

* add test for blockParentRootIndicesBucket

* fix changelog

* fix build

* address kasey's comments

* fix build

* add trace span to blockRootsBySlotRange

---------

Co-authored-by: Radosław Kapka <rkapka@wp.pl>
Co-authored-by: Preston Van Loon <pvanloon@offchainlabs.com>

cmd/beacon-chain/flags/base.go

@@ -296,4 +296,16 @@ var (
 		Usage: "Directory for the slasher database",
 		Value: cmd.DefaultDataDir(),
 	}
+	// BeaconDBPruning enables the pruning of beacon db.
+	BeaconDBPruning = &cli.BoolFlag{
+		Name: "beacon-db-pruning",
+		Usage: "Enables pruning of beacon db beyond MIN_EPOCHS_FOR_BLOCK_REQUESTS duration. This is an opt-in feature," +
+			" and should only be enabled if operators doesn't require historical data.",
+	}
+	// PrunerRetentionEpochs defines the retention period for the pruner service in terms of epochs.
+	PrunerRetentionEpochs = &cli.Uint64Flag{
+		Name: "pruner-retention-epochs",
+		Usage: "Specifies the retention period for the pruner service in terms of epochs. " +
+			"If this value is less than MIN_EPOCHS_FOR_BLOCK_REQUESTS, it will be ignored.",
+	}
 )

cmd/beacon-chain/main.go

@@ -82,6 +82,8 @@ var appFlags = []cli.Flag{
 	flags.LocalBlockValueBoost,
 	flags.MinBuilderBid,
 	flags.MinBuilderDiff,
+	flags.BeaconDBPruning,
+	flags.PrunerRetentionEpochs,
 	cmd.BackupWebhookOutputDir,
 	cmd.MinimalConfigFlag,
 	cmd.E2EConfigFlag,

cmd/beacon-chain/usage.go

@@ -133,6 +133,8 @@ var appHelpFlagGroups = []flagGroup{
 			flags.MinBuilderBid,
 			flags.MinBuilderDiff,
 			flags.JwtId,
+			flags.BeaconDBPruning,
+			flags.PrunerRetentionEpochs,
 			checkpoint.BlockPath,
 			checkpoint.StatePath,
 			checkpoint.RemoteURL,