test-runner: allow radio remove failure

This is somewhat of an open issue/TODO but for now this avoids
the exception caused by trying to remove a radio that has been
moved to a namespace. Once a radio is moved hwsim loses that phy
and can no longer interact with it. This causes the Destroy()
method call to fail.

tools/test-runner

@@ -395,7 +395,12 @@ class VirtualRadio(Radio):
 	def __del__(self):
 		super().__del__()
 
-		self._radio.remove()
+		# If the radio was moved into a namespace this will fail
+		try:
+			self._radio.remove()
+		except:
+			pass
+
 		self._radio = None
 
 	def __str__(self):