S3: prevent deleting buckets with object locking (#7434)

* prevent deleting buckets with object locking

* addressing comments

* Update s3api_bucket_handlers.go

* address comments

* early return

* refactor

* simplify

* constant

* go fmt

weed/command/benchmark.go

@@ -141,7 +141,7 @@ func runBenchmark(cmd *Command, args []string) bool {
 		fmt.Fprintln(os.Stderr, "Error: -readOnly and -writeOnly are mutually exclusive.")
 		return false
 	}
-	
+
 	doWrite := true
 	doRead := true
 	if *b.readOnly {