Remove ARDUINO form factor from RBLAB_BLENANO2

Remove the ARDUINO form factor from the RBLAB_BLENANO2 since it
does not have D11, D12, D14, D15 defined and does not physically have
the arduino form factor.

Author: c1728p9

targets/targets.json

@@ -4576,7 +4576,6 @@
         "macros_add": ["TARGET_RBLAB_BLENANO"]
     },
     "RBLAB_BLENANO2": {
-        "supported_form_factors": ["ARDUINO"],
         "inherits": ["MCU_NRF52832"],
         "release_versions": ["5"],
         "device_name": "nRF52832_xxAA"