ensure problematic ha service is stopped during update

ensure problematic ha service is stopped during update

Add a postinst file which stops, if running, the ha service before it
configures pve-cluster and starts them again, if enabled.
Do this only if the version installed before the upgrade is <= 2.0-3

dpkg-query has Version and Config-Version

Version is at this time the new unpacked version already, so we need
to check both to catch all cases.

Signed-off-by: Thomas Lamprecht <t.lamprecht@proxmox.com>