Remove an over-zealous sanity check. It's OK to have no test

switches, in case we only have wide area nodes. Of course, snmpit
won't _do_ anything, but it shouldn't be an error to run it.

tbsetup/snmpit_lib.pm

@@ -285,11 +285,6 @@ sub getTestSwitches () {
 	push @switches, $row[0];
     }
 
-    # Sanity check - make sure we actually found some
-    if (!@switches) {
-	die "Failed to find testswitches\n";
-    }
-
     return @switches;
 }