deleting guest to member migration (#5579)

Co-authored-by: Cyril PETEL <[email protected]>

Author: crlptl

menu/navigation.json

@@ -434,10 +434,6 @@
                     "label": "Permission sets",
                     "slug": "permission-sets"
                   },
-                  {
-                    "label": "IAM Guests to Members migration",
-                    "slug": "guests-to-members-migration"
-                  },
                   {
                     "label": "Reproducing roles and Project-scoped API keys with IAM",
                     "slug": "reproduce-roles-project-api-keys"