Remove 1 second delay before running netsh

Remove 1 second delay before running netsh

When running various netsh commands before each 1 second sleep is added.
As more netsh commands are run, especially for Wintun adapters, that can
add to a noticable delayed connecting time.

This should be safe. No problems were found in tests and all netsh
commands executed properly with delay removed. Also, no delays are used
in a similar code in interactive service and netsh command executions
are guarded with a semaphore.

Instead of removing management_sleep(1), management_sleep(0) is used as
a replacement to allow processing any pending actions on the management
interface without any wait.

Signed-off-by: Domagoj Pensa <domagoj@pensa.hr>
Acked-by: Lev Stipakov <lstipakov@gmail.com>
Message-Id: <20201224115910.10129-1-domagoj@pensa.hr>
URL: https://www.mail-archive.com/openvpn-devel@lists.sourceforge.net/msg21405.html
Signed-off-by: Gert Doering <gert@greenie.muc.de>
(cherry picked from commit b1a8213ee3fe35a4617608ec7653e4dffea79207)