gh_action/test-on-iotlab: update available boards

Author: aabadie

.github/workflows/test-on-iotlab.yml

@@ -36,15 +36,11 @@ jobs:
           - riot: dwm1001
             iotlab:
               archi: dwm1001:dw1000
-              site: saclay
+              site: lille
           - riot: iotlab-m3
             iotlab:
               archi: m3:at86rf231
               site: saclay
-          - riot: nrf51dk
-            iotlab:
-              archi: nrf51dk:ble
-              site: saclay
           - riot: nrf52dk
             iotlab:
               archi: nrf52dk:ble
@@ -53,10 +49,6 @@ jobs:
             iotlab:
               archi: nrf52840dk:multi
               site: saclay
-          - riot: nrf52832-mdk
-            iotlab:
-              archi: nrf52832mdk:ble
-              site: saclay
           - riot: nucleo-wl55jc
             iotlab:
               archi: nucleo-wl55jc:stm32wl