Deprecated the commerce connection's 'forVendor' methods

Deprecated com.coremedia.livecontext.ecommerce.common.CommerceConnection#getServiceForVendor and com.coremedia.livecontext.ecommerce.common.CommerceConnection#getQualifiedServiceForVendor . Only use the com.coremedia.livecontext.ecommerce.common.ForVendor annotation to customize the com.coremedia.blueprint.base.livecontext.client.common.GenericCommerceConnection . Resort to com.coremedia.blueprint.base.livecontext.ecommerce.common.CommerceServicesForVendor if legacy commerce connections are used.

(CMS-19123)