[#1337] shard: Disable background rebuild

Since `frostfs-cli control shards rebuild` command was added,
there is no need for background rebuild now.
For failover tests used used value 1 to rebuild only schema change.

Signed-off-by: Dmitrii Stepanov <d.stepanov@yadro.com>

pkg/local_object_storage/blobstor/common/rebuild.go

@@ -11,17 +11,10 @@ type RebuildRes struct {
 	FilesRemoved uint64
 }
 
-type RebuildAction struct {
-	SchemaChange bool
-
-	FillPercent      bool
-	FillPercentValue int
-}
-
 type RebuildPrm struct {
 	MetaStorage   MetaStorage
 	WorkerLimiter ConcurrentWorkersLimiter
-	Action        RebuildAction
+	FillPercent   int
 }
 
 type MetaStorage interface {