remove gateway completely (#15929)

cmd/erasure-server-pool.go

@@ -42,8 +42,6 @@ import (
 )
 
 type erasureServerPools struct {
-	GatewayUnsupported
-
 	poolMetaMutex sync.RWMutex
 	poolMeta      poolMeta
 	serverPools   []*erasureSets
@@ -2132,12 +2130,6 @@ func (z *erasureServerPools) HealObject(ctx context.Context, bucket, object, ver
 	}
 }
 
-// GetMetrics - returns metrics of local disks
-func (z *erasureServerPools) GetMetrics(ctx context.Context) (*BackendMetrics, error) {
-	logger.LogIf(ctx, NotImplemented{})
-	return &BackendMetrics{}, NotImplemented{}
-}
-
 func (z *erasureServerPools) getPoolAndSet(id string) (poolIdx, setIdx, diskIdx int, err error) {
 	for poolIdx := range z.serverPools {
 		format := z.serverPools[poolIdx].format