Remove WS tag loader contribution from nuxeo-platform-tag-core

The following error appears and a lot of unit tests, for instance the REST API ones:

= Component Loading Status: Pending: 0 / Missing: 1 / Unstarted: 0 / Total: 183
  * test:tags-contrib references missing [target=org.nuxeo.ecm.platform.ws.session.WSRemotingSessionManagerImpl;point=loaders]

This is because "ws-tag-loader-contrib.xml" is deployed by nuxeo-platform-tag-core and the RestServerFeature, for instance, loads "org.nuxeo.ecm.platform.tag" but not "org.nuxeo.ecm.platform.ws".

This must have been forgotten when removing the webservices, see NXP-22799.