Disable cluster restart attempt

ci/testnet-manager.sh

@@ -340,6 +340,10 @@ sanity-or-restart)
   else
     echo "+++ Sanity failed, updating the network"
     $metricsWriteDatapoint "testnet-manager sanity-failure=1"
+
+    # TODO: Restore attempt to restart the cluster before recreating it
+    #       See https://github.com/solana-labs/solana/issues/3774
+    if false; then
       if start "" update; then
         echo Update successful
       else
@@ -347,6 +351,9 @@ sanity-or-restart)
         $metricsWriteDatapoint "testnet-manager update-failure=1"
         start
       fi
+    else
+      start
+    fi
   fi
   ;;
 esac