fix: cleanup [1316]

```
$ make busted-util
/usr/local/openresty/luajit/bin/rover exec bin/busted "spec/threescale_utils_spec.lua"
●●●
3 successes / 0 failures / 0 errors / 0 pending : 0.023738 seconds
```

Author: abarrak

gateway/src/apicast/threescale_utils.lua

@@ -194,7 +194,7 @@ function _M.error(resilient, ...)
   else
     ngx.status = ngx.HTTP_INTERNAL_SERVER_ERROR
     ngx.say(...)
-    if not resilient or resilient == nil then
+    if not resilient then
       ngx.exit(ngx.status)
     end
   end

spec/threescale_utils_spec.lua

@@ -16,7 +16,7 @@ describe('3scale utils', function()
             stub(ngx, 'say', function(...) return nil end)
             local exit = spy.on(ngx, 'exit', function(s) return 'exited!' end)
 
-            local error = _M.error(false, 'cache issue ' .. 'host:' .. 6379)
+            local error = _M.error(nil, 'cache issue ' .. 'host:' .. 6379)
 
             assert.spy(ngx.exit).was_called(1)
             assert.spy(ngx.say).was.called_with('cache issue ' .. 'host:' .. 6379)