Merge branch 'psi-board-mile-ancestors' into 'master'

Include parent milestones in board list items

See merge request gitlab-org/gitlab!57366

ee/app/assets/javascripts/boards/graphql/group_board_milestones.query.graphql

 query GroupBoardMilestones($fullPath: ID!, $searchTerm: String) {
   group(fullPath: $fullPath) {
-    # TODO: add includeAncestors: https://gitlab.com/gitlab-org/gitlab/-/issues/323433
-    milestones(searchTitle: $searchTerm) {
+    milestones(includeAncestors: true, searchTitle: $searchTerm) {
       nodes {
         id
         title