nova ec2-api: DescribeTags search filter should be AND

[Burt Holzman]

From: http://docs.aws.amazon.com/AWSEC2/latest/APIReference/ApiReference-query-DescribeTags.html

You can specify multiple filters (for example, specify a specific resource type and tag values that contain the string database). The response includes information for a tag only if it matches all the filters that you specified. If there's no match, no special message is returned, the response is simply empty.

We just pass the search filters up to db._instance_metadata_get_all, which does a OR of the search filters, but EC2 requires an AND.

[OpenStack Infra (hudson-openstack)]

Fix proposed to branch: master
Review: https://review.openstack.org/35822

[Burt Holzman (holzman)]

This was fixed in https://review.openstack.org/36244