Add the old DRBD secrets reservation code to mocked config
Add the old DRBD secrets reservation code to mocked config

.. so that the unit tests work without the presence of WConfd.

Also fix mocked GenerateMAC, which used _temporary_ids by mistake in the
original ConfigWriter.

Signed-off-by: Petr Pudlak <9d19625f8ee825a2c398462ed335cbcf98f79c32@google.com>
Reviewed-by: Klaus Aehlig <4ce51de36d9068cd7db2eec1151e0f3f95419008@google.com>

apyrgio/ganeti,ganeti/ganeti,mbakke/ganeti,andir/ganeti,yiannist/ganeti,mbakke/ganeti,andir/ganeti,apyrgio/ganeti,leshchevds/ganeti,onponomarev/ganeti,bitemyapp/ganeti,grnet/snf-ganeti,onponomarev/ganeti,ganeti/ganeti,ganeti-github-testing/ganeti-test-1,ganeti/ganeti,yiannist/ganeti,leshchevds/ganeti,leshchevds/ganeti,grnet/snf-ganeti,ganeti-github-testing/ganeti-test-1,bitemyapp/ganeti,mbakke/ganeti,dimara/ganeti,dimara/ganeti,andir/ganeti,yiannist/ganeti