add search model group permission to ml_read_access role (#2855) (#2858)

* add search model group permission to ml_read_access role

Signed-off-by: Bhavana Ramaram <rbhavna@amazon.com>
(cherry picked from commit 0bc7158)

Co-authored-by: Bhavana Ramaram <rbhavna@amazon.com>

config/roles.yml

@@ -258,6 +258,7 @@ ml_read_access:
   reserved: true
   cluster_permissions:
     - 'cluster:admin/opensearch/ml/stats/nodes'
+    - 'cluster:admin/opensearch/ml/model_groups/search'
     - 'cluster:admin/opensearch/ml/models/get'
     - 'cluster:admin/opensearch/ml/models/search'
     - 'cluster:admin/opensearch/ml/tasks/get'