cmd/utils: add check on fd hard limit, skip test if below target (#15684)

* cmd/utils: Add check on hard limit, skip test if below target

* cmd/utils: Cross platform compatible fd limit test

* cmd/utils: Remove syscall.Rlimit in test

* cmd/utils: comment fd utility method

cmd/utils/fdlimit_unix.go

@@ -48,3 +48,13 @@ func getFdLimit() (int, error) {
 	}
 	return int(limit.Cur), nil
 }
+
+// getFdMaxLimit retrieves the maximum number of file descriptors this process is
+// allowed to request for itself.
+func getFdMaxLimit() (int, error) {
+	var limit syscall.Rlimit
+	if err := syscall.Getrlimit(syscall.RLIMIT_NOFILE, &limit); err != nil {
+		return 0, err
+	}
+	return int(limit.Max), nil
+}