Cleanup Sahara tags

In 504e8ecb66 we split up each Sahara
component into its own deliverable. As a temporary measure, each
component received all the tags from the former single deliverable.

Removal of tags is motivated as follows:
* assert:follows-standard-deprecation and assert-supports-upgrade should
  only be applied to services
* tc:approved-release is generally only applied to the main
  repo/deliverable of a project

Also, for consistency with other projects, docs entry is removed for all
but the main Sahara service (even though those central docs do somewhat
deal with the other components).

Change-Id: I654b09cdf6872196bb691cafb525d2bda4b152c1

reference/projects.yaml

@@ -4186,38 +4186,20 @@ sahara:
     sahara-dashboard:
       repos:
         - openstack/sahara-dashboard
-      docs:
-        contributor: https://docs.openstack.org/sahara/latest/
-        api: https://developer.openstack.org/api-ref/data-processing/
       tags:
-        - tc:approved-release
         - vulnerability:managed
-        - assert:follows-standard-deprecation
-        - assert:supports-upgrade
         - stable:follows-policy
     sahara-extra:
       repos:
         - openstack/sahara-extra
-      docs:
-        contributor: https://docs.openstack.org/sahara/latest/
-        api: https://developer.openstack.org/api-ref/data-processing/
       tags:
-        - tc:approved-release
         - vulnerability:managed
-        - assert:follows-standard-deprecation
-        - assert:supports-upgrade
         - stable:follows-policy
     sahara-image-elements:
       repos:
         - openstack/sahara-image-elements
-      docs:
-        contributor: https://docs.openstack.org/sahara/latest/
-        api: https://developer.openstack.org/api-ref/data-processing/
       tags:
-        - tc:approved-release
         - vulnerability:managed
-        - assert:follows-standard-deprecation
-        - assert:supports-upgrade
         - stable:follows-policy
     sahara-tests:
       repos: