Revert "samba36: add hotplug support"

Revert "samba36: add hotplug support"

This reverts commit fd569e5e9d0a46ea957cb253e97a4b3ea8c2c540.

After an extra review & discussion few concerns were raised regarding
that feature:
1) It reacts to hotplug.d "block" events instead of more accurate (but
   currently unavailable) "mount" events.
2) It requires *something* to mount block device before samba hotplug.d
   gets fired. Otherwise samba_add_section() will just return.
3) It doesn't reload Samba which some users may expect
4) It operates on /etc/ which is not a right place for autogenerated
   ephemeral config.
5) It doesn't include any cleanup for non-existing shares.

Cc: Rosy Song <rosysong@rosinson.com>
Cc: Jo-Philipp Wich <jo@mein.io>
Signed-off-by: Rafał Miłecki <rafal@milecki.pl>